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  • 1. Baev, A.
    et al.
    Gelmukhanov, Faris
    KTH, Tidigare Institutioner (före 2005), Kemi.
    Kimberg, Viktor
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Ågren, Hans
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Nonlinear propagation of strong multi-mode fields2003Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 36, s. 3761-3774Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We develop a strict theory of nonlinear propagation of few interacting stronglight beams. The key idea of our approach is a self-consistent solution ofthe nonlinear wave equation and the density matrix equations of the materialbeyond the rotatory wave approximation. We assume a Fourier expansion ofthe density matrixwhich goes beyond the conventionalTaylor expansions of thepolarization over the field amplitudeswhich is inadequate for the field strengthsthat we are interested in. Two qualitatively different situations are considered,with and without phase matching. Unlike in our previous paper (Baev et al2003 J. Opt. Soc. Am. B at press) devoted to the three-photon (TP) absorptioninduced upconverted lasing, we obtain here a strict solution for the nonlinearinteraction between different light beams. The general theory is applied to anumerical study of the role of saturation in TP photoabsorption by an organicchromophore in solution.

  • 2. Baev, A.
    et al.
    Kimberg, Viktor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Polyutov, Sergey
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Gelmukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Bi-directional description of amplified spontaneous emission induced by three-photon absorption2005Ingår i: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 22, nr 2, s. 385-393Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     A semiclassical dynamic theory of the nonlinear propagation of a few interacting intense light pulses is applied to study the nonlinear counterpropagation of amplified spontaneous emission (ASE) induced by three-photon absorption of short intense laser pulses in a chromophore solution. Several important results from the modeling are reached for the ASE process developing in the regime of strong saturation. Accounting for ASE in both forward and backward directions with respect to the pump pulse results in a smaller efficiency of nonlinear conversion for the forward ASE compared with the case in which forward emission is considered alone, something that results from the partial repump of the absorbed energy to the backward ASE component; the overall efficiency is nevertheless higher than for the forward emission considered alone. The efficiency of nonlinear conversion of the pump energy to the counterpropagating ASE pulses is strongly dependent on the concentration of active molecules so that a particular combination of concentration versus cell length optimizes the conversion coefficient. Under certain specified conditions, the ASE effect is found to be oscillatory; the origin of oscillations is dynamical competition between stimulated emission and off-resonant absorption. This result can be considered one of the possible explanations of the temporal fluctuations of the forward ASE pulse [Nature 415, 767 (2002)].

  • 3.
    Barreau, Lou
    et al.
    Department of Chemistry, University of California, Berkeley, California 94720, USA; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
    Ross, Andrew D.
    Department of Chemistry, University of California, Berkeley, California 94720, USA; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Teoretisk kemi och biologi.
    Krasnov, Pavel
    International Research Center of Spectroscopy and Quantum Chemistry-IRC SQC, Siberian Federal University, Krasnoyarsk 660041, Russia.
    Blinov, Svyatoslav
    International Research Center of Spectroscopy and Quantum Chemistry-IRC SQC, Siberian Federal University, Krasnoyarsk 660041, Russia.
    Neumark, Daniel M.
    Department of Chemistry, University of California, Berkeley, California 94720, USA; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
    Leone, Stephen R.
    Department of Chemistry, University of California, Berkeley, California 94720, USA; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Department of Physics, University of California, Berkeley, California 94720, USA.
    Core-excited states of Formula Presented probed with soft-x-ray femtosecond transient absorption of vibrational wave packets2023Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 108, nr 1, artikel-id 012805Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A vibrational wavepacket in Formula Presented is created by impulsive stimulated Raman scattering with a few-cycle infrared pulse and mapped simultaneously onto five sulfur core-excited states using table-top soft x-ray transient absorption spectroscopy between 170 to 200 eV. The femtosecond vibrations induce real-time energy shifts of the x-ray absorption, whose amplitude depend strongly on the nature of the core-excited state. The pump laser intensity is used to control the number of vibrational states in the superposition, thereby accessing core-excited levels for various extensions of the S-F stretching motion. This enables the determination of the relative core-level potential energy gradients for the symmetric stretching mode, in good agreement with TDDFT calculations. This experiment demonstrates a new means of characterizing core-excited potential energy curves.

  • 4.
    C. Couto, Rafael
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Vaz da Cruz, Vinícius
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ertan, Emelie
    Eckert, Sebastian
    Fondell, Mattis
    Dantz, Marcus
    Kennedy, Brian
    Schmitt, Thorsten
    Pietzsch, Annette
    F. Guimarães, Freddy
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Gel’mukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Odelius, Michael
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Föhlisch, Alexander
    Selective gating to vibrational modes through resonant X-ray scattering2017Ingår i: Nature Communications, E-ISSN 2041-1723, Vol. 8, s. 14165-1-14165-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dynamics of fragmentation and vibration of molecular systems with a large number of coupled degrees of freedom are key aspects for understanding chemical reactivity and properties. Here we present a resonant inelastic X-ray scattering (RIXS) study to show how it is possible to break down such a complex multidimensional problem into elementary components. Local multimode nuclear wave packets created by X-ray excitation to different core-excited potential energy surfaces (PESs) will act as spatial gates to selectively probe the particular ground-state vibrational modes and, hence, the PES along these modes. We demonstrate this principle by combining ultra-high resolution RIXS measurements for gas-phase water with state-of-the-art simulations.

  • 5.
    Couto, Rafael C.
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Universidade Federal Goiás, Brasilia.
    Guarise, Marco
    Nicolaou, Alessandro
    Jaouen, Nicolas
    Chiuzbaian, Gheorghe S.
    Luening, Jan
    Ekholm, Victor
    Rubensson, Jan-Erik
    Sathe, Conny
    Hennies, Franz
    Guimaraes, Freddy F.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Gel'mukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Journel, Loic
    Simon, Marc
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Coupled electron-nuclear dynamics in resonant 1 sigma -> 2 pi x-ray Raman scattering of CO molecules2016Ingår i: Physical Review A, ISSN 2469-9926, Vol. 93, nr 3, artikel-id 032510Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a detailed experimental-theoretical analysis of O K-edge resonant 1 sigma-2 pi inelastic x-ray scattering (RIXS) from carbon monoxide with unprecedented energy resolution. We employ high-level ab initio calculations to compute the potential energy curves of the states involved in the RIXS process and simulate the measured RIXS spectra using the wave-packet-propagation formalism, including Coulomb coupling in the final-state manifold. The theoretical analysis allows us to explain all the key features of the experimental spectra, including some that were not seen before. First, we clearly show the interference effect between different RIXS channels corresponding to the transition via orthogonal (1)Pi(x) and (1)Pi(y) core-excited states of CO. Second, the RIXS region of 13 eV energy loss presents a triple structure, revealed only by the high-resolution measurement. In previous studies, this region was attributed solely to a valence state. Here we show a strong Coulomb mixing of the Rydberg and valence final states, which opens the forbidden RIXS channels to the "dark" final Rydberg states and drastically changes the RIXS profile. Third, using a combination of high-resolution experiment and high-level theory, we improve the vertical bar 4 sigma(-1)2 pi(1)> final-state potential-energy curve by fitting its bottom part with the experiment. Also, the coupling constants between Rydberg and valence states were refined via comparison with the experiment. Our results illustrate the large potential of the RIXS technique for advanced studies of highly excited states of neutral molecules.

  • 6.
    Couto, Rafael C.
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Univ Fed Goias, Brazil.
    Guarise, Marco
    Nicolaou, Alessandro
    Jaouen, Nicolas
    Chiuzbaian, Gheorghe S.
    Luening, Jan
    Ekholm, Victor
    Rubensson, Jan-Erik
    Sathe, Conny
    Hennies, Franz
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Guimaraes, Freddy F.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Gel'mukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Journel, Loic
    Simon, Marc
    Anomalously strong two-electron one-photon X-ray decay transitions in CO caused by avoided crossing2016Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 6, artikel-id 20947Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The unique opportunity to study and control electron-nuclear quantum dynamics in coupled potentials offered by the resonant inelastic X-ray scattering (RIXS) technique is utilized to unravel an anomalously strong two-electron one-photon transition from core-excited to Rydberg final states in the CO molecule. High-resolution RIXS measurements of CO in the energy region of 12-14 eV are presented and analyzed by means of quantum simulations using the wave packet propagation formalism and ab initio calculations of potential energy curves and transition dipole moments. The very good overall agreement between the experimental results and the theoretical predictions allows an in-depth interpretation of the salient spectral features in terms of Coulomb mixing of "dark" with "bright" final states leading to an effective two-electron one-photon transition. The present work illustrates that the improved spectral resolution of RIXS spectra achievable today may call for more advanced theories than what has been used in the past.

  • 7.
    Cui, Jun Jie
    et al.
    School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China.
    Cheng, Yongjun
    School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China.
    Wang, Xin
    School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China.
    Li, Zheng
    State Key Laboratory for Mesoscopic Physics and Collaborative Innovation Center of Quantum Matter, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China, Shanxi; Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China.
    Rohringer, Nina
    Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607, Hamburg, Germany.
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Teoretisk kemi och biologi.
    Zhang, Song Bin
    School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China.
    Proposal for Observing XUV-Induced Rabi Oscillation Using Superfluorescent Emission2023Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 4, artikel-id 043201Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Intense x-ray and extreme ultraviolet (XUV) light sources have been available for decades, however, due to weak nonlinear interaction in the XUV photon energy range, observation of Rabi oscillation induced by XUV pulse remains a very challenging experimental task. Here we suggest a scheme where photoionization of a He medium by an intense XUV pump pulse is followed by a strong population inversion and Rabi oscillation at the He+(1s-3p) transition and is accompanied by superfluorescence (SF) of the 7.56 eV pulse at the He+(3p-2s) transition. Our numerical simulations show that the Rabi oscillation at the He+(1s-3p) transition induced by an XUV pulse with photon energy 48.36 eV results in significant signatures in the SF spectra, allowing us to identify and characterize the XUV induced Rabi-oscillatory regime. The proposed scheme provides a sensitive tool to monitor and control ultrafast nonlinear dynamics in atoms and molecules triggered by intense XUV.

  • 8. Céolin, D.
    et al.
    Rueff, J. -P
    Zimin, Andrei
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Federal University, Russian Federation.
    Morin, P.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Federal University, Russian Federation.
    Polyutov, S.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Federal University, Russian Federation.
    Gelmukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Federal University, Russian Federation.
    Far-Zone Resonant Energy Transfer in X-ray Photoemission as a Structure Determination Tool2017Ingår i: The Journal of Physical Chemistry Letters, E-ISSN 1948-7185, Vol. 8, nr 12, s. 2730-2734Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Near-zone Förster resonant energy transfer is the main effect responsible for excitation energy flow in the optical region and is frequently used to obtain structural information. In the hard X-ray region, the Förster law is inadequate because the wavelength is generally shorter than the distance between donors and acceptors; hence, far-zone resonant energy transfer (FZRET) becomes dominant. We demonstrate the characteristics of X-ray FZRET and its fundamental differences with the ordinary near-zone resonant energy-transfer process in the optical region by recording and analyzing two qualitatively different systems: high-density CuO polycrystalline powder and SF6 diluted gas. We suggest a method to estimate geometrical structure using X-ray FZRET employing as a ruler the distance-dependent shift of the acceptor core ionization potential induced by the Coulomb field of the core-ionized donor.

  • 9.
    da Cruz, Vinicius Vaz
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Royal Inst Technol, Theoret Chem & Biol, S-10691 Stockholm, Sweden..
    Ertan, Emelie
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Ignatova, Nina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Inst Nanotechnol Spect & Quantum Chem, Krasnoyarsk 660041, Russia..
    Couto, Rafael C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Polyutov, Sergey
    Siberian Fed Univ, Inst Nanotechnol Spect & Quantum Chem, Krasnoyarsk 660041, Russia..
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Inst Nanotechnol Spect & Quantum Chem, Krasnoyarsk 660041, Russia..
    Gel'mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Royal Inst Technol, Theoret Chem & Biol, S-10691 Stockholm, Sweden.
    Anomalous polarization dependence in vibrationally resolved resonant inelastic x-ray scattering of H2O2018Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 98, nr 1, artikel-id 012507Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is well established that different electronic channels, in resonant inelastic x-ray scattering (RIXS), display different polarization dependences due to different orientations of their corresponding transition dipole moments in the molecular frame. However, this effect does not influence the vibrational progression in the Franck-Condon approximation. We have found that the transition dipole moments of core excitation and deexcitation experience ultrafast rotation during dissociation in the intermediate core-excited state. This rotation makes the vibrational progression in RIXS sensitive to the polarization of the x-ray photons. We study the water molecule, in which the effect is expressed in RIXS through the dissociative core-excited state where the vibrational scattering anisotropy is accompanied also by violation of parity selection rules for the vibrations.

  • 10.
    da Cruz, Vinicius Vaz
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Gel'mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Lab Nonlinear Opt & Spect, Krasnoyarsk 660041, Russia.
    Eckert, Sebastian
    Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Iannuzzi, Marcella
    Univ Zurich, Phys Chem Inst, CH-8057 Zurich, Switzerland..
    Ertan, Emelie
    Stockholm Univ, Dept Phys, AlbaNova Univ Ctr, S-10691 Stockholm, Sweden..
    Pietzsch, Annette
    Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Couto, Rafael C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Niskanen, Johannes
    Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.;Univ Turku, Dept Phys & Astron, FI-20014 Turunyliopisto, Finland..
    Fondell, Mattis
    Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Dantz, Marcus
    Paul Scherrer Inst, Photon Sci Div, CH-5232 Villigen, Switzerland..
    Schmitt, Thorsten
    Paul Scherrer Inst, Photon Sci Div, CH-5232 Villigen, Switzerland..
    Lu, Xingye
    Paul Scherrer Inst, Photon Sci Div, CH-5232 Villigen, Switzerland..
    McNally, Daniel
    Paul Scherrer Inst, Photon Sci Div, CH-5232 Villigen, Switzerland..
    Jay, Raphael M.
    Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Kimberg, Victor
    Foehlisch, Alexander
    Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Odelius, Michael
    Stockholm Univ, Dept Phys, AlbaNova Univ Ctr, S-10691 Stockholm, Sweden..
    Probing hydrogen bond strength in liquid water by resonant inelastic X-ray scattering2019Ingår i: Nature Communications, E-ISSN 2041-1723, Vol. 10, artikel-id 1013Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Local probes of the electronic ground state are essential for understanding hydrogen bonding in aqueous environments. When tuned to the dissociative core-excited state at the O1s pre-edge of water, resonant inelastic X-ray scattering back to the electronic ground state exhibits a long vibrational progression due to ultrafast nuclear dynamics. We show how the coherent evolution of the OH bonds around the core-excited oxygen provides access to high vibrational levels in liquid water. The OH bonds stretch into the long-range part of the potential energy curve, which makes the X-ray probe more sensitive than infra-red spectroscopy to the local environment. We exploit this property to effectively probe hydrogen bond strength via the distribution of intramolecular OH potentials derived from measurements. In contrast, the dynamical splitting in the spectral feature of the lowest valence-excited state arises from the short-range part of the OH potential curve and is rather insensitive to hydrogen bonding.

  • 11.
    da Cruz, Vinicius Vaz
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Ignatova, Nina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Krasnoyarsk 660041, Russia.;Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia..
    Couto, Rafael C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Fedotov, Daniil A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Krasnoyarsk 660041, Russia..
    Rehn, Dirk R.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Savchenko, Viktoriia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Krasnoyarsk 660041, Russia.;Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia..
    Norman, Patrick
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Ågren, Hans
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Polyutov, Sergey
    Siberian Fed Univ, Krasnoyarsk 660041, Russia.;Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia..
    Niskanen, Johannes
    Univ Turku, Dept Phys & Astron, FI-20014 Turun, Finland.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Eckert, Sebastian
    Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Jay, Raphael M.
    Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Fondell, Mattis
    Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Schmitt, Thorsten
    Paul Scherrer Inst, Photon Sci Div, CH-5232 Villigen, Switzerland..
    Pietzsch, Annette
    Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Foehlisch, Alexander
    Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Gel'mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Krasnoyarsk 660041, Russia.;Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia..
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Krasnoyarsk 660041, Russia.;Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia..
    Nuclear dynamics in resonant inelastic X-ray scattering and X-ray absorption of methanol2019Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 150, nr 23, artikel-id 234301Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on a combined theoretical and experimental study of core-excitation spectra of gas and liquid phase methanol as obtained with the use of X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). The electronic transitions are studied with computational methods that include strict and extended second-order algebraic diagrammatic construction [ADC(2) and ADC(2)-x], restricted active space second-order perturbation theory, and time-dependent density functional theory-providing a complete assignment of the near oxygen K-edge XAS. We show that multimode nuclear dynamics is of crucial importance for explaining the available experimental XAS and RIXS spectra. The multimode nuclear motion was considered in a recently developed "mixed representation" where dissociative states and highly excited vibrational modes are accurately treated with a time-dependent wave packet technique, while the remaining active vibrational modes are described using Franck-Condon amplitudes. Particular attention is paid to the polarization dependence of RIXS and the effects of the isotopic substitution on the RIXS profile in the case of dissociative core-excited states. Our approach predicts the splitting of the 2a RIXS peak to be due to an interplay between molecular and pseudo-atomic features arising in the course of transitions between dissociative core- and valence-excited states. The dynamical nature of the splitting of the 2a peak in RIXS of liquid methanol near pre-edge core excitation is shown. The theoretical results are in good agreement with our liquid phase measurements and gas phase experimental data available from the literature.

  • 12.
    Dong, Xiao Xia
    et al.
    Shaanxi Normal Univ, Sch Phys & Informat Technol, Xian 710119, Peoples R China..
    Liu, Yan Rong
    Shaanxi Normal Univ, Sch Phys & Informat Technol, Xian 710119, Peoples R China..
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ IRC SQC, Int Res Ctr Spect & Quantum Chem, Krasnoyarsk 660041, Russia..
    Vendrell, Oriol
    Heidelberg Univ, Inst Phys Chem, Theoret Chem, D-69120 Heidelberg, Germany..
    Wu, Yong
    Inst Appl Phys & Computat Math, Beijing 100088, Peoples R China.;Peking Univ, Ctr Appl Phys & Technol, HEDPS, Beijing 100084, Peoples R China..
    Wang, Jian Guo
    Inst Appl Phys & Computat Math, Beijing 100088, Peoples R China..
    Chen, Jing
    Inst Appl Phys & Computat Math, Beijing 100088, Peoples R China.;Peking Univ, Ctr Appl Phys & Technol, HEDPS, Beijing 100084, Peoples R China..
    Zhang, Song Bin
    Shaanxi Normal Univ, Sch Phys & Informat Technol, Xian 710119, Peoples R China..
    Carrier-envelope-phase measurement of sub-cycle UV pulses using angular photofragment distributions2022Ingår i: Communications Physics, E-ISSN 2399-3650, Vol. 5, nr 1, artikel-id 181Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Carrier-envelope-phase (CEP) of sub-cycle ultraviolet (UV) pulse strongly influences the dynamics of quantum systems, but its characterization is not accessible experimentally. Here we investigate photodissociation of a diatomic molecule from its ground-rovibrational state in a linearly polarized weak sub-cycle UV pulse with a controlled CEP. The angular distribution of photofragments shows an asymmetric profile deviating from the well-known cos(2-) or sin(2)-like ones, which can be identified as a way to imprint CEP. We unveil that such an effect stems from the temporal neighboring rotational excitation by molecular permanent dipole interaction through the joint contributions between counter-rotating and rotating terms. This in turn, opens different pathways in photodissociation dynamics. Given that the temporal excitation between various states with close energies can be manipulated by CEP of subcycle UV pulses, our results pave ways for understanding and manipulating electron, nuclear and their joint dynamics with variation of CEP of attosecond pulses.

  • 13. Ertan, Emelie
    et al.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Fed Univ, Russia.
    Gel'mukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Fed Univ, Russia.
    Hennies, Franz
    Rubensson, Jan-Erik
    Schmitt, Thorsten
    Strocov, Vladimir N.
    Zhou, Kejin
    Iannuzzi, Marcella
    Foehlisch, Alexander
    Odelius, Michael
    Pietzsch, Annette
    Theoretical simulations of oxygen K-edge resonant inelastic x-ray scattering of kaolinite2017Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, nr 14, artikel-id 144301Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Near-edge x-ray absorption fine structure (NEXAFS) and resonant inelastic x-ray scattering (RIXS) measurements at the oxygen K edge were combined with theoretical spectrum simulations, based on periodic density functional theory and nuclear quantum dynamics, to investigate the electronic structure and chemical bonding in kaolinite Al2Si2O5(OH)(4). We simulated NEXAFS spectra of all crystallographically inequivalent oxygen atoms in the crystal and RIXS spectra of the hydroxyl groups. Detailed insight into the ground-state potential energy surface of the electronic states involved in the RIXS process were accessed by analyzing the vibrational excitations, induced by the core excitation, in quasielastic scattering back to the electronic ground state. In particular, we find that the NEXAFS pre-edge is dominated by features related to OH groups within the silica and alumina sheets, and that the vibrational progression in RIXS can be used to selectively probe vibrational modes of this subclass of OH groups. The signal is dominated by the OH stretching mode, but also other lower vibrational degrees of freedom, mainly hindered rotational modes, contribute to the RIXS signal.

  • 14.
    Ertan, Emelie
    et al.
    Stockholm university.
    Savchenko, Viktoriia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Federal University.
    Ignatova, Nina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Federal University.
    da Cruz, Vinicius Vaz
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Couto, Rafael C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Eckert, Sebastian
    Institut für Physik und Astronomie, Universität Potsdam.
    Fondell, Mattis
    Dantz, Marcus
    Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut.
    Kennedy, Brian
    Institute for Methods and Instrumentation in Synchrotron Radiation Research G- ISRR, Helmholtz-Zentrum Berlin für Materialien und Energie.
    Schmitt, Thorsten
    Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut.
    Pietzsch, Annette
    Institute for Methods and Instrumentation in Synchrotron Radiation Research G- ISRR, Helmholtz-Zentrum Berlin für Materialien und Energie.
    Föhlisch, Alexander
    Institut für Physik und Astronomie, Universität Potsdam.
    Gel'mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Odelius, Michael
    Stockholm university.
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Ultrafast dissociation features in RIXS spectra of the water molecule2018Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this combined theoretical and experimental study we report on an analysis of the resonant inelastic X-ray scattering spectra (RIXS) of gas phase water via the lowest dissociative core-excited state |1sO-14a11〉. We focus on the spectral feature near the dissociation limit of the electronic ground state. We show that the narrow atomic-like peak consists of the overlapping contribution from the RIXS channels back to the ground state and to the first valence excited state |1b1-14a11〉 of the molecule. The spectral feature has signatures of ultrafast dissociation (UFD) in the core-excited state, as we show by means of ab initio calculations and time-dependent nuclear wave packet simulations. We show that the electronically elastic RIXS channel gives substantial contribution to the atomic-like resonance due to the strong bond length dependence of the magnitude and orientation of the transition dipole moment. By studying the RIXS for an excitation energy scan over the core-excited state resonance, we can understand and single out the molecular and atomic-like contributions in the decay to the lowest valence-excited state. Our study is complemented by a theoretical discussion of RIXS in the case of the isotope substituted water (HDO and D2O) where the nuclear dynamics is significantly affected by the heavier fragments' mass.

  • 15. Feifel, R.
    et al.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Baev, Alexander
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Gel'mukhanov, Faris
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Ågren, Hans
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Miron, C.
    Ohrwall, G.
    Piancastelli, M. N.
    Sorensen, S. L.
    Karlsson, L.
    Svensson, S.
    Profile of resonant photoelectron spectra versus the spectral function width and photon frequency detuning2004Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 70, nr 3Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The outermost, singly ionized valence state of N-2, the X (2)Sigma(g)(+) state, is investigated in detail as a function of the photon frequency bandwidth for core excitation to the N 1s-->pi(*) resonance, where the photon frequency is tuned in between the first two vibrational levels of this bound intermediate electronic state. We find a strong, nontrivial dependence of the resulting resonant photoemission spectral profile on the monochromator function width and the frequency of its peak position. For narrow bandwidth excitation we observe a well resolved vibrational fine structure in the final electron spectrum, which for somewhat broader bandwidths gets smeared out into a continuous structure. For even broader monochromator bandwidths, it converts again into a well resolved vibrational progression. In addition, spectral features appearing below the adiabatic transition energy of the ground state of N-2(+) are observed for broadband excitation. A model taking into account the interplay of the partial scattering cross section with the spectral function is presented and applied to the X (2)Sigma(g)(+) final state of N-2(+).

  • 16. Gejo, T.
    et al.
    Oura, M.
    Tokushima, T.
    Horikawa, Y.
    Arai, H.
    Shin, S.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Kosugi, N.
    Resonant inelastic x-ray scattering and photoemission measurement of O2: Direct evidence for dependence of Rydberg-valence mixing on vibrational states in O 1 s → Rydberg states2017Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 147, nr 4, artikel-id 044310Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-resolution resonant inelastic x-ray scattering (RIXS) and low-energy photoemission spectra of oxygen molecules have been measured for investigating the electronic structure of Rydberg states in the O 1s → σ∗ energy region. The electronic characteristics of each Rydberg state have been successfully observed, and new assignments are made for several states. The RIXS spectra clearly show that vibrational excitation is very sensitive to the electronic characteristics because of Rydberg-valence mixing and vibronic coupling in O2. This observation constitutes direct experimental evidence that the Rydberg-valence mixing characteristic depends on the vibrational excitation near the avoided crossing of potential surfaces. We also measured the photoemission spectra of metastable oxygen atoms (O) from O2 excited to 1s → Rydberg states. The broadening of the 4p Rydberg states of O∗ has been found with isotropic behavior, implying that excited oxygen molecules undergo dissociation with a lifetime of the order of 10 fs in 1s → Rydberg states.

  • 17.
    Gel'mukhanov, Faris
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Liu, X. J.
    Prumper, G.
    Tanaka, T.
    Hoshino, M.
    Tanaka, H.
    Ueda, K.
    Young's double-slit experiment using two-center core-level photoemission: Photoelectron recoil effects2007Ingår i: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 156, s. 265-269Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Core-level photoemission from N-2 can be considered an analogue of Young's double-slit experiment (YDSE) in which the double-slit is replaced by a pair of N 1s orbitals. The measured ratio between the 1 sigma(g) and 1 sigma(u) photoionization cross-sections oscillates as a function of photoelectron momentum, due to two-center YDSE interference, exhibiting a remarkable dependence on the vibrational sub-levels of the core ionized state. We theoretically demonstrate that the recoil of the photoelectron given to the ionized N atom strongly influences this interference pattern. The reason for this is that the momentum transfer affects the phases of the photoionization amplitudes.

  • 18.
    Gelmukhanov, Faris
    et al.
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Kimberg, Victor
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Ågren, Hans
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    X-ray Doppler spectroscopy of ultrafast fragmentation2004Ingår i: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Chem. Phys., Vol. 299, s. 253-258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Doppler effects are now commonly observed for Auger resonances of dissociating atoms in randomly oriented molecules. The physics behind the, yet not observed, Doppler effect for fixed-in-space molecules is different in that there will appear extra Doppler resonances resulting from the diffractional scattering of the Auger electrons by the surrounding atoms. It is argued that as these resonances will show maxima in the bond directions their measurement by current energy and angular resolved electron-ion coincidence experiments will provide structural probing. It is also shown that the electronic Doppler effect caused by nuclear vibrations can be observed also for bound nuclear states making use of electron-ion coincidence measurements. Optimal conditions for such measurements prevail when the scattering duration is comparable with a vibrational period.

  • 19.
    Gelmukhanov, Faris
    et al.
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Kimberg, Viktor
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Ågren, Hans
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Structure determination through measurements of Doppler-split Augerresonances in fixed-in-space molecules2004Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 69, nr 2, s. 020501(R)-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Auger resonances of dissociating atoms in randomly oriented molecules experience large electronic Dopplershifts. We predict that when fixed-in-space molecules are considered there will appear extra Doppler resonancesresulting from the diffractional scattering of the Auger electrons by the surrounding atoms. Theseresonances show sharp maxima in bond directions, something that makes them very promising as probes forlocal molecular structure using current energy- and angular-resolved electron-ion coincidence experiments.

  • 20.
    Gel'mukhanov, Faris
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Teoretisk kemi och biologi. International Research Center of Spectroscopy and Quantum Chemistry - IRC SQC, Siberian Federal University, 660041 Krasnoyarsk, Russia.
    Liu, Ji Cai
    School of Mathematics and Physics, North China Electric Power University, 102206 Beijing, China; Hebei Key Laboratory of Physics and Energy Technology, North China Electric Power University, 071000 Baoding, China.
    Krasnov, Pavel
    International Research Center of Spectroscopy and Quantum Chemistry - IRC SQC, Siberian Federal University, 660041 Krasnoyarsk, Russia.
    Ignatova, Nina
    International Research Center of Spectroscopy and Quantum Chemistry - IRC SQC, Siberian Federal University, 660041 Krasnoyarsk, Russia.
    Rubensson, Jan Erik
    Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala, Sweden.
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Teoretisk kemi och biologi.
    Nonlocal resonant inelastic x-ray scattering2023Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 108, nr 5, artikel-id 052820Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the description of resonant inelastic x-ray scattering (RIXS) from inversion-symmetric molecules the small core-level splitting is typically neglected. However, the spacing Δ between gerade and ungerade core levels in homonuclear diatomic molecules can be comparable with the lifetime broadening of the intermediate core-excited state Γ. We show that when Δ∼Γ the scattering becomes nonlocal in the sense that x-ray absorption at one atomic site is followed by emission at the other one. This is manifested in an unusual dependence of the RIXS cross section on the sum of the momenta of incoming and outgoing x-ray photons k+k′, contrary to the normal k-k′ dependence in the conventional local RIXS theory. The nonlocality of the scattering influences strongly the scattering angle and excitation energy dependence of the intensity ratio between parity forbidden and allowed RIXS channels. Numerical simulations for N2 show that this effect can readily be measured at present-day x-ray radiation facilities.

  • 21.
    Gel'mukhanov, Faris
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.;Siberian Fed Univ, Int Res Ctr Spect & Quantum Chem IRC SQC, Krasnoyarsk 660041, Russia.;Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia..
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Polyutov, Sergey P.
    Siberian Fed Univ, Int Res Ctr Spect & Quantum Chem IRC SQC, Krasnoyarsk 660041, Russia.;Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia..
    Foehlisch, Alexander
    Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.;Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Int Res Ctr Spect & Quantum Chem IRC SQC, Krasnoyarsk 660041, Russia..
    Dynamics of resonant x-ray and Auger scattering2021Ingår i: Reviews of Modern Physics, ISSN 0034-6861, E-ISSN 1539-0756, Vol. 93, nr 3, artikel-id 035001Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Anoverview of both experimental and theoretical results in the field of resonant scattering of tunable soft and hard x-ray radiation is presented, with a main focus on the closely related processes of resonant inelastic x-ray scattering (RIXS) and resonant Auger scattering (RAS). The review starts with an overview of fundamental dynamical aspects of RIXS illustrated for different systems. A detailed analysis of case studies with increasing complexity, considering both gas-phase and condensed matter (liquids and solids) applications, is given. In the review, the most important achievements in investigations of coupled electron-nuclear dynamics and structural aspects in studies of liquids and solids over the last two decades are outlined. To give a perspective on the insights from RIXS and RAS, the x-ray results are discussed against the background of complementary experimental techniques like vibrational infrared absorption and Raman spectroscopy, as well as small-angle x-ray and neutron scattering. Finally, recent achievements in time-resolved studies based on x-ray free-electron lasers are described.

  • 22.
    Guimaraes, Freddy Fernandes
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Felicissimo, Viviane C.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Gelmukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Cesar, A.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Infrared–x-ray pump-probe spectroscopy of the NO molecule2005Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 72, nr 1, artikel-id 012714Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two color infrared-x-ray pump-probe spectroscopy of the NO molecule is studied theoretically and numerically in order to obtain a deeper insight of the underlying physics and of the potential of this suggested technology. From the theoretical investigation a number of conclusions could be drawn: It is found that the phase of the infrared field strongly influences the trajectory of the nuclear wave packet, and hence, the x-ray spectrum. The trajectory experiences fast oscillations with the vibrational frequency with a modulation due to the anharmonicity of the potential. The dependences of the x-ray spectra on the delay time, the duration, and the shape of the pulses are studied in detail. It is shown that the x-ray spectrum keep memory about the infrared phase after the pump field left the system. This memory effect is sensitive to the time of switching-off the pump field and the Rabi frequency. The phase effect takes maximum value when the duration of the x-ray pulse is one-fourth of the infrared field period, and can be enhanced by a proper control of the duration and intensity of the pump pulse. The manifestation of the phase is different for oriented and disordered molecules and depends strongly on the intensity of the pump radiation.

  • 23.
    Guimaraes, Freddy Fernandes
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO).
    Felicissimo, Viviane C.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Gel'mukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Cesar, A.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Phase sensitive x-ray absorption driven by strong infrared fields2005Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 71, nr 4, artikel-id 043407Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper it is demonstrated that electron vibrational absorption of molecules driven by strong IR field provides rich physical interpretations of dynamical processes on a short time scale. The phase of an infrared field influences strongly the trajectory of the nuclear wave packet and the probing spectrum. It is shown that the probe spectrum keeps memory of the infrared phase even after that the pump field left the system. The phase effect takes maximum value when the duration of the probe pulse is of the order of the infrared field period, and can be enhanced by a proper control of the duration and intensity of the pump pulse. The phase effect is different for oriented and disordered molecules and depends strongly on the intensity of pump radiation. It can be an effective tool to study charge transfer processes like proton transfer in hydrogen bonded networks.

  • 24.
    Guimaraes, Freddy
    et al.
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Kimberg, Vikctor
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Gel'mukhanov, Faris
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Ågren, Hans
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Two-color phase-sensitive x-ray pump-probe spectroscopy2004Ingår i: Phys. Rev. A, ISSN 1050-2947, Vol. 70, s. 062504-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    X-ray pump-probe spectroscopy is studied theoretically. It is shown that two-color-optical+x-ray-excitation with constant phase of the pump radiation exhibits strong interference between the one- and two-photon excitation channels. This effect is found to be large for both long and short pump pulses, while the interference vanishes for x-ray pulses longer than one cycle of the pump field. It is predicted that the spectral shape of x-ray absorption is strongly influenced by the absolute phase of the pump light. A strong sensitivity of the x-ray absorption and/or photoionization profile to the phase and detuning of the pump field is predicted, as well as to the duration of the x-ray pulse. Our simulations display oscillations of x-ray absorption as a function of the delay time. This effect allows the synchronization of the x-ray pulse relative to the "comb" of the pump radiation. The interference pattern copies the temporal and space distribution of the pump field. We pay special attention to the role of molecular orientation for the interference effect.

  • 25.
    Ignatova, Nina
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Federal University.
    da Cruz, Vinícius V.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Couto, Rafael C.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ertan, Emelie
    Stockholm university.
    Odelius, Michael
    Stockholm university.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Guimarães, Freddy F.
    Zimin, Andrei
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Federal University.
    Polyutov, Sergey
    Siberian Federal University.
    Gel’mukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Infrared-pump–x-ray-probe spectroscopy of vibrationally excited molecules2017Ingår i: Physical Review A, ISSN 2469-9926, Vol. 95, nr 4, artikel-id 042502Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We develop a theory of infrared (IR)-pump–x-ray-probe spectroscopy for molecular studies. We illustrate advantages of the proposed scheme by means of numerical simulations employing a vibrational wave packet technique applied to x-ray absorption and resonant inelastic x-ray scattering (RIXS) spectra of the water molecule vibrationally excited by a preceding IR field. The promotion of the vibrationally excited molecule to the dissociative 1a−114a1 and bound 1a−112b2 core-excited states with qualitatively different shapes of the potential energy surfaces creates nuclear wave packets localized along and between the OH bonds, respectively. The projection of these wave packets on the final vibrational states, governed by selection and propensity rules, results in spatial selectivity of RIXS sensitive to the initial vibrationally excited state, which makes it possible to probe selectively the ground state properties along different modes. In addition, we propose to use RIXS as a tool to study x-ray absorption from a selected vibrational level of the ground state when the spectral resolution is sufficiently high to resolve vibrational overtones. The proposed technique has potential applications for advanced mapping of multidimensional potential energy surfaces of ground and core-excited molecular states, for symmetry-resolved spectroscopy, and for steering chemical reactions.

  • 26.
    Ignatova, Nina
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Federal University.
    V. Cruz, Vinícius
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Couto, Rafael C.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ertan, Emelie
    Zimin, Andrey
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    F. Guimarães, Freddy
    Polyutov, Sergey
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Odelius, Michael
    Gel’mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Gradual collapse of nuclear wave functions regulated by frequency tuned X-ray scattering2017Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 7, nr 43891Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As is well established, the symmetry breaking by isotope substitution in the water molecule results in localisation of the vibrations along one of the two bonds in the ground state. In this study we find that this localisation may be broken in excited electronic states. Contrary to the ground state, the stretching vibrations of HDO are delocalised in the bound core-excited state in spite of the mass difference between hydrogen and deuterium. The reason for this effect can be traced to the narrow “canyon-like” shape of the potential of the state along the symmetric stretching mode, which dominates over the localisation mass-difference effect. In contrast, the localisation of nuclear motion to one of the HDO bonds is preserved in the dissociative core-excited state . The dynamics of the delocalisation of nuclear motion in these core-excited states is studied using resonant inelastic X-ray scattering of the vibrationally excited HDO molecule. The results shed light on the process of a wave function collapse. After core-excitation into the state of HDO the initial wave packet collapses gradually, rather than instantaneously, to a single vibrational eigenstate.

  • 27. Kikas, A.
    et al.
    Kaambre, T.
    Saar, A.
    Kooser, K.
    Nommiste, E.
    Martinson, I.
    Kimberg, Victor
    KTH, Tidigare Institutioner (före 2005), Kemi.
    Polyutov, Sergey
    KTH, Tidigare Institutioner (före 2005), Kemi.
    Gel'mukhanov, Faris
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Resonant inelastic x-ray scattering at the F 1s photoabsorption edge in LiF: Interplay of excitonic and conduction states, and Stokes' doubling2004Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, nr 8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The excitation-decay processes at the F 1s photoabsorption edge in LiF crystal are studied using resonant inelastic x-ray scattering spectroscopy. The Raman-type linear dispersion and the narrowing of the x-ray fluorescence peak are observed at resonant excitation. A theoretical model based on the Kramers-Heisenberg formula describes well the main features in fluorescence spectra and allows one to separate the contributions of the exciton and the conduction states in the scattering spectra. At the same time, the role of the shape of the spectral distribution within the incident radiation is emphasized as being critically sensitive to the number, kind, and onset of the spectral features which finally appear in the scattering spectra at a particular incident photon energy, particularly in the subthreshold excitation region.

  • 28. Kimberg, V.
    et al.
    Lindblad, A.
    Soederstroem, J.
    Travnikova, O.
    Nicolas, C.
    Sun, Yuping
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Gel'mukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Kosugi, N.
    Miron, C.
    Single-Molecule X-Ray Interferometry: Controlling Coupled Electron-Nuclear Quantum Dynamics and Imaging Molecular Potentials by Ultrahigh-Resolution Resonant Photoemission and Ab Initio Calculations2013Ingår i: Physical Review X, E-ISSN 2160-3308, Vol. 3, nr 1, artikel-id 011017Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports an advanced study of the excited ionic states of the gas-phase nitrogen molecule in the binding-energy region of 22-34 eV, combining ultrahigh-resolution resonant photoemission (RPE) and ab initio configuration-interaction calculations. The RPE spectra are recorded for nine photon energies within the N 1s -> pi* absorption resonance of N-2 by using a photon bandwidth that is considerably smaller than lifetime broadening, and the dependence on excitation energy of the decay spectra is analyzed and used for the first assignment of 12 highly overlapped molecular states. The effect on the RPE profile of avoided curve crossings between the final N-2(+) ionic states is discussed, based on theoretical simulations that account for vibronic coupling, and compared with the experimental data. By use of synchrotron radiation with high spectral brightness, it is possible to selectively promote the molecule to highly excited vibrational sublevels of a core-excited electronic state, thereby controlling the spatial distribution of the vibrational wave packets, and to accurately image the ionic molecular potentials. In addition, the mapping of the vibrational wave functions of the core-excited states using the bound final states with far-from-equilibrium bond lengths has been achieved experimentally for the first time. Theoretical analysis has revealed the rich femtosecond nuclear dynamics underlying the mapping phenomenon. DOI: 10.1103/PhysRevX.3.011017

  • 29.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO).
    Pulse Propagation in Nonlinear Media and Photonic Crystals2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The present thesis is devoted to theoretical studies of pulse propagation of light through linear and nonlinear media, and of light-induced nuclear dynamics.

    The first part of the thesis addresses propagation of light pulses in linear periodical media - photonic crystals. The main accent was put on studies of the angular properties of two qualitatively different types of photonic crystals: holographic photonic crystals, and impurity band based photonic crystals. The anisotropy of band structure, group velocity and pulse delay with respect to the light polarization are analyzed.

    In the second part of the thesis a strict theory of nonlinear propagation of a few strong interacting light beams is presented. The key idea of this approach is a self-consistent solution of the nonlinear wave equation and the density matrix equations of the material. This technique is applied to studies of dynamics of cavityless lasing generated by ultra-fast multi-photon excitation. It is shown that interaction of co- and counter-propagating pulses of amplified spontaneous emission (ASE) affects the dynamics and efficiency of nonlinear conversion. Our dynamical theory allows to explain the asymmetric spectral properties of the forward and backward ASE pulses, which were observed in recent experiment with different dye molecules. It is shown that the ASE spectral profile changes drastically when the pump intensity approaches the threshold level. The effect of the temporal self-pulsation of ASE is studied in detail.

    The third part of the thesis is devoted to light-induced nuclear dynamics. Time- and frequency-resolved X-ray spectroscopy of molecules driven by strong and coherent infrared (IR) pulses shows that the phase of the IR field strongly influences the trajectory of the nuclear wave packet, and hence, the X-ray spectrum. Such a dependence arises due to the interference of one (X-ray) and two-photon (X-ray + IR) excitation channels. The phase of the light influences the dynamics also when the Rabi frequency approaches the vibrational frequency, breaking down the rotating-wave approximation. The probe X-ray spectra are also sensitive to the delay time, the duration, and the shape of the pulses. The evolution of the nuclear wave packets in the dissociative core-excited state affects the dynamics of resonant Auger scattering from fixed-in-space molecules. One of the important dynamical effects is the atomic-like resonance which experiences electronic Doppler shift. We predict that the scattering of the Auger electrons by nearby atoms leads to new Doppler shifted resonances. These extra resonances show sharp maxima in the bond directions, which makes them very promising as probes for local molecular structure using energy and angular resolved electron-ion coincidence techniques. Our theory provides prediction of several new effects, but also results that are in good agreement with the available experimental data.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 30.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Pulse propagation in photonic crystals and nonlinear media2005Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The present thesis is devoted to theoretical studies of light pulse propagation through different linear and nonlinear media. One dimensional holographic photonic crystals and one dimensional impurity band based photonic crystals are investigated as linear media. The effects of angular dependence of the band structures and pulse delay with respect to the light polarization are analyzed. A strict theory of nonlinear propagation of a few strong interacting light beams is presented and applied in the field of nonlinear optics. The key idea of this approach is a self-consistent solution of the nonlinear wave equation and the density matrix equations of the material beyond the so-called rotating wave approximation. The results of numerical studies led to a successful interpretation of recent experimental data [Nature, 415:767, 2002]. A theoretical study of the NO molecule by means of two-color infrared -- X-ray pump probe spectroscopy is presented. It was found that the phase of the infrared field strongly influences the trajectory of the nuclear wave packet, and hence, the X-ray spectrum. The dependence of the X-ray spectra on the delay time, the duration and the shape of the pulses are studied.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 31. Kimberg, Victor
    et al.
    Gejo, Tatsuo
    Oura, Masaki
    Tokushima, Takashi
    Horikawa, Yuka
    Arai, Hidemi
    Shin, Shik
    Kosugi, Nobuhiro
    Rydberg-valence mixing and interchannel coupling in resonant oxygen 1s inelastic x-ray scattering of O_22012Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 85, nr 3Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rydberg-valence (RV) mixing and doublet-quartet (DQ) interchannel coupling in the core-excited states of triplet open-shell O2 are experimentally and theoretically unveiled through the resonant inelastic x-ray scattering around the O 1s→σ∗u resonance. Ab initio calculations explain complicated excitation energy dependence of the spectral profile by the interplay of the DQ interchannel coupling under the presence of the RV mixing. Complicated intermediate states with valence and/or Rydberg character are successfully analyzed through the filtering of pure valence and pure Rydberg final states.

  • 32.
    Kimberg, Victor
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Gelmukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Angular anisotropy of the delay time of short pulses in impurity band based photonic crystals2005Ingår i: Journal of Optics. A, Pure and applied optics, ISSN 1464-4258, E-ISSN 1741-3567, Vol. 7, nr 3, s. 118-122Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate the transmission of short pulses through one-dimensional impurity band based photonic crystals. We found a strong dependence of the delay time on the angle of incidence. The delay time is larger for larger incident angles for the transverse electrical mode, while the delay time of the transverse magnetic mode has a qualitatively different angular dependence, especially in the region below the Brewster angle. The strong anisotropy of the delay time is traced to the anisotropy of the group velocity which is directly related to the angular dependence of the impurity band structure.

  • 33.
    Kimberg, Victor
    et al.
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Gelmukhanov, Faris
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Ågren, Hans
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Pent, E.
    Plekhanov, A.
    Kuchin, I.
    Rodionov, M.
    Shelkovnikov, V.
    Angular properties of band structures in one-dimensional holographic photonic crystals2004Ingår i: Journal of Optics. A, Pure and applied optics, ISSN 1464-4258, E-ISSN 1741-3567, Vol. 6, nr 10, s. 991-996Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One-dimensional photonic crystals with continuous distribution of the dielectric constant were fabricated by the use of photopolymer materials and laser holography. The angular dependence of light propagation through the system was studied experimentally and theoretically. It is shown that the Brewster angles for different bands are different, in contrast to the conventional two-layer Bragg reflector with a step-like distribution of the dielectric constant. Comparison of the theory with experimental data allowed us to define the parameters of the hologram-the dielectric contrast and the shrinkage of the structure.

  • 34.
    Kimberg, Victor
    et al.
    KTH, Skolan för bioteknologi (BIO).
    Guimaraes, Freddy Fernandes
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Felicissimo, Viviane C.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Gel'mukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Phase-sensitive wave-packet dynamics caused by a breakdown of the rotating-wave approximation2006Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 73, nr 2, artikel-id 023409Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The water dimer driven by strong infrared field is studied in the two-vibrational mode approximation. A pump pulse excites the OH vibrational modes and creates a coherent superposition of vibrational states of the low-frequency OO mode. The solution of the Schrodinger equation in the adiabatic approximation shows a strong sensitivity of the OO vibrational wave-packet dynamics to the absolute phase of the pump field. This effect appears due to a break down of the rotating-wave approximation when the Rabi frequency of the OH vibrational transition approaches the frequency of the OH mode. The violation of the rotating wave approximation modifies considerably the interaction of the probe radiation with the laser-driven molecule.

  • 35. Kimberg, Victor
    et al.
    Miron, Catalin
    Molecular potentials and wave function mapping by high-resolution electron spectroscopy and ab initio calculations2013Ingår i: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 195, s. 301-306Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The recent development of high brightness 3rd generation soft X-ray sources and high energy resolution electron spectrometers made it possible to accurately trace quantum phenomena associated to the vibrational dynamics in core-excited molecules. The present paper reviews the recent results on mapping of vibrational wave functions and molecular potentials based on electron spectroscopy. We discuss and compare the mapping phenomena in various systems, stressing the advantages of the resonant X-ray scattering for studying of the nuclear dynamics and spectroscopic constants of small molecules. The experimental results discussed in the paper are most often accompanied by state-of-the-art ab initio calculations allowing for a deeper understanding of the quantum effects. Besides its fundamental interest, the vibrational wave function mapping is shown to be useful for the analysis of core- and valence-excited molecular states based on the reflection principle.

  • 36.
    Kimberg, Victor
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Polyutov, Sergey
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Gel'mukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Baev, Alexander
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Zheng, Q.D.
    Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo.
    He, G. S.
    Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo.
    Dynamics of cavityless lasing generated by ultrafast multiphoton excitation2006Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 74, nr 3, artikel-id 033814Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A dynamical theory is developed with the purpose of explaining recent experimental results on multiphoton-excited amplified stimulated emission (ASE). Several conspicuous features of this experiment are analyzed, like the threshold dependence of the spectral profile on the pump intensity, and spectral shifts of the ASE pulses co- and counterpropagating relative to the pump pulse. Two models are proposed and evaluated, one based on the isolated molecule and another which involves solvent interaction. The spectral shift between the forward and backward ASE pulses arises in the first model through the competition between the ASE transitions from the pumped vibrational levels and from the bottom of the excited-state well, while in the solvent-related model the dynamical solute-solvent interaction leads to a relaxed excited state, producing an additional ASE channel. In the latter model the additional redshifted ASE channel makes the dynamics of ASE essentially different from that in the molecular model because the formation of the relaxed state takes a longer time. The variation of the pump intensity influences strongly the relative intensities of the different ASE channels and, hence, the spectral shape of ASE in both models. The regime of ASE changes character when the pump intensity crosses a threshold value. Such a phase transition occurs when the ASE rate approaches the rate of vibrational relaxation or the rate of solute-solvent relaxation in the first excited state.

  • 37.
    Kimberg, Victor
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Max Planck Institute for the Physics of Complex Systems, Germany.
    Rohringer, N.
    Stochastic stimulated electronic x-ray Raman spectroscopy2016Ingår i: Structural Dynamics, E-ISSN 2329-7778, Vol. 3, nr 3, artikel-id 34101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Resonant inelastic x-ray scattering (RIXS) is a well-established tool for studying electronic, nuclear, and collective dynamics of excited atoms, molecules, and solids. An extension of this powerful method to a time-resolved probe technique at x-ray free electron lasers (XFELs) to ultimately unravel ultrafast chemical and structural changes on a femtosecond time scale is often challenging, due to the small signal rate in conventional implementations at XFELs that rely on the usage of a monochromator setup to select a small frequency band of the broadband, spectrally incoherent XFEL radiation. Here, we suggest an alternative approach, based on stochastic spectroscopy, which uses the full bandwidth of the incoming XFEL pulses. Our proposed method is relying on stimulated resonant inelastic x-ray scattering, where in addition to a pump pulse that resonantly excites the system a probe pulse on a specific electronic inelastic transition is provided, which serves as a seed in the stimulated scattering process. The limited spectral coherence of the XFEL radiation defines the energy resolution in this process and stimulated RIXS spectra of high resolution can be obtained by covariance analysis of the transmitted spectra. We present a detailed feasibility study and predict signal strengths for realistic XFEL parameters for the CO molecule resonantly pumped at the O1s→π* transition. Our theoretical model describes the evolution of the spectral and temporal characteristics of the transmitted x-ray radiation, by solving the equation of motion for the electronic and vibrational degrees of freedom of the system self consistently with the propagation by Maxwell equations.

  • 38. Kimberg, Victor
    et al.
    Rohringer, Nina
    Amplified X-Ray Emission from Core-Ionized Diatomic Molecules2013Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 110, nr 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We predict high-gain x-ray lasing in molecular nitrogen by ultrafast core ionization with an x-ray free-electron laser source. To estimate the spectral and temporal output of this molecular x-ray laser, we solve generalized Maxwell-Bloch equations, keeping track of the electronic and nuclear degrees of freedom. The spectrum of the amplified x-ray emission shows a strong dependence on the gain-length product. Whereas the emission at small gain length is similar to the relatively broad x-ray fluorescence band, the spectrum is determined by a single frequency in the linear gain region. The vibrational wave packet dynamics during the x-ray emission process is examined. By preparation of the initial vibrational quantum state, the x-ray emission frequency can be tuned within the fluorescence band. The present scheme is applicable to other homo- and heteronuclear diatomic systems, thereby extending the spectral range of coherent x-ray radiation sources based on amplification on bound transitions.

  • 39.
    Kimberg, Victor
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Sanchez-Gonzalez, Alvaro
    Mercadier, Laurent
    Weninger, Clemens
    Lutman, Alberto
    Ratner, Daniel
    Coffee, Ryan
    Bucher, Maximilian
    Mucke, Melanie
    Agåker, Marcus
    Såthe, Conny
    Bostedt, Christoph
    Nordgren, Joseph
    Rubensson, Jan Erik
    Rohringer, Nina
    Stimulated X-ray Raman scattering: a critical assessment of the building block of nonlinear X-ray spectroscopy2016Ingår i: Faraday discussions, ISSN 1359-6640, E-ISSN 1364-5498Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the invention of femtosecond X-ray free-electron lasers (XFELs), studies of light-induced chemical reaction dynamics and structural dynamics reach a new era, allowing for time-resolved X-ray diffraction and spectroscopy. To ultimately probe coherent electron and nuclear dynamics on their natural time and length scales, coherent nonlinear X-ray spectroscopy schemes have been proposed. In this contribution, we want to critically assess the experimental realisation of nonlinear X-ray spectroscopy at current-day XFEL sources, by presenting first experimental attempts to demonstrate stimulated resonant X-ray Raman scattering in molecular gas targets.

  • 40. Kimberg, Victor
    et al.
    Zhang, S B
    Rohringer, Nina
    X-ray lasing in the CO molecule2013Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 46, nr 16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We theoretically demonstrate the feasibility of x-ray lasing in the CO molecule by the core ionization of the C K- and O K-shell by x-ray free-electron laser sources. Our numerical simulations are based on the solution of generalized Maxwell–Bloch equations, accounting for the electronic and nuclear degrees of freedom. The amplified x-ray emission pulses have an extremely narrow linewidth of about 0.1 eV and a pulse duration shorter than 30 fs. We compare x-ray lasing transitions to the three lowest electronic states of singly ionized CO. The dependence of the lasing efficiency on the spectral width of the x-ray fluorescence band, value and orientation of the electronic transition dipole moment, lifetime of the core-excited state and the duration of the pump pulse is analysed. Using a pre-aligned molecular ensemble substantially increases the amplified emission. Moreover, by controlling the molecular alignment and thereby the alignment of the transition dipole moment polarization, the control of the emitted x-ray radiation is achievable. Preparing the initial vibrational quantum state, the x-ray emission frequency can be tuned within the fluorescence band. The present scheme is applicable to other diatomic systems, thereby extending the spectral range of coherent x-ray radiation sources based on stimulated x-ray emission on bound transitions.

  • 41. Kimberg, Victor
    et al.
    Zhang, Song Bin
    Rohringer, Nina
    X-ray lasing in diatomic molecules2014Ingår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 488, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We predict high-gain x-ray lasing in diatomic molecules by ultrafast core ionization of the C K- and O K-edges in CO and the N K-edge in N2 with an x-ray free-electron laser source. To estimate the spectral and temporal output of this molecular x-ray laser, we solve generalized Maxwell-Bloch equations, keeping track of the electronic and nuclear degrees of freedom. Despite the broad fluorescence bandwidth, the amplified x-ray emission shows a narrow spectrum. By controlling the molecular alignment and thereby the alignment of the transition dipole moment polarization and emission energy control of the x-ray laser radiation is achievable.

  • 42. Lindblad, Andreas
    et al.
    Kimberg, V
    Söderström, Johan
    Nicolas, C
    Travnikova, O
    Kosugi, N
    Gel'mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Miron, C
    Vibrational scattering anisotropy in O2 -- €”dynamics beyond the Born–Oppenheimer approximation2012Ingår i: New Journal of Physics, E-ISSN 1367-2630, Vol. 14, nr 11Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Born–Oppenheimer and Franck–Condon approximations are two major concepts in the interpretation of electronic excitations and modeling of spectroscopic data in the gas and condensed phases. We report large variations of the anisotropy parameter (β) for the fully resolved vibrational sub-states of the X2Πg electronic ground state of O+2 populated by participator resonant Auger decay following excitations of K-shell electrons into the σ☆ resonance by monochromatic x-rays. Decay spectra for light polarization directions parallel and perpendicular to the electron detection axis recorded at four different excitation energies in the vicinity of the O 1s → σ☆ transition are presented. Breakdown of the Born–Oppenheimer approximation is for the first time selectively observed for the lower vibrational sub-states, where two quantum paths—resonant and direct—leading to the same final cationic state exist. The higher vibrational sub-states can only be populated by resonant photoemission; hence no interference between these channels can occur.

  • 43. Liu, J. -C
    et al.
    Ignatova, N.
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Teoretisk kemi och biologi.
    Krasnov, P.
    Föhlisch, A.
    Simon, M.
    Gel'mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Teoretisk kemi och biologi.
    Time-resolved study of recoil-induced rotation by X-ray pump - X-ray probe spectroscopy2022Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 24, nr 11, s. 6627-6638Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Modern stationary X-ray spectroscopy is unable to resolve rotational structure. In the present paper, we propose to use time-resolved two color X-ray pump-probe spectroscopy with picosecond resolution for real-time monitoring of the rotational dynamics induced by the recoil effect. The proposed technique consists of two steps. The first short pump X-ray pulse ionizes the valence electron, which transfers angular momentum to the molecule. The second time-delayed short probe X-ray pulse resonantly excites a 1s electron to the created valence hole. Due to the recoil-induced angular momentum the molecule rotates and changes the orientation of transition dipole moment of core-excitation with respect to the transition dipole moment of the valence ionization, which results in a temporal modulation of the probe X-ray absorption as a function of the delay time between the pulses. We developed an accurate theory of the X-ray pump-probe spectroscopy of the recoil-induced rotation and study how the energy of the photoelectron and thermal dephasing affect the structure of the time-dependent X-ray absorption using the CO molecule as a case-study. We also discuss the feasibility of experimental observation of our theoretical findings, opening new perspectives in studies of molecular rotational dynamics. 

  • 44.
    Liu, Ji Cai
    et al.
    School of Mathematics and Physics, North China Electric Power University, 102206 Beijing, China; Hebei Key Laboratory of Physics and Energy Technology, North China Electric Power University, 071000 Baoding, China.
    Gel'mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Teoretisk kemi och biologi. International Research Center of Spectroscopy and Quantum Chemistry-IRC SQC, Siberian Federal University, 660041 Krasnoyarsk, Russia.
    Polyutov, Sergey
    International Research Center of Spectroscopy and Quantum Chemistry-IRC SQC, Siberian Federal University, 660041 Krasnoyarsk, Russia.
    Krasnov, Pavel
    International Research Center of Spectroscopy and Quantum Chemistry-IRC SQC, Siberian Federal University, 660041 Krasnoyarsk, Russia.
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Teoretisk kemi och biologi.
    Complementarity in which-path resonant Auger scattering2024Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 109, nr 2, artikel-id 023116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Different types of Young's double-slit experiments contain a significant amount of both particle and wave information running from full-particle to full-wave knowledge depending on the experimental conditions. We study the Young's double-slit interference in resonant Auger scattering from homonuclear diatomic molecules where opposite Doppler shifts for the dissociating atomic slits provide path information. Different quantitative formulation of Bohr's complementarity principle - path information vs interference - is applied to two types of resonant Auger scattering experiments, with fixed-in-space and randomly oriented molecules. Special attention is paid to the orientational dephasing in conventional Auger experiments with randomly oriented molecules. Our quantitative formulation of the complementarity is compared with the formulation made earlier by Greenberger and Yasin [D. M. Greenberger and A. Yasin, Phys. Lett. A 128, 391 (1988)0375-960110.1016/0375-9601(88)90114-4].

  • 45.
    Liu, Ji-Cai
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Nicolas, Christophe
    Sun, Yu-Ping
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Flammini, Roberto
    O'Keeffe, Patrick
    Avaldi, Lorenzo
    Morin, Paul
    Kimberg, Victor
    Kosugi, Nobuhiro
    Gel'mukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Miron, Catalin
    Multimode Resonant Auger Scattering from the Ethene Molecule2011Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 115, nr 18, s. 5103-5112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Resonant Auger spectra of ethene molecule have been measured with vibrational resolution at several excitation energies in the region of the C1s(-1)1b(2g)(π*) resonance. The main features observed in the experiment have been assigned and are accurately interpreted on the basis of ab initio multimode calculations. Theory explains the extended vibrational distribution of the resonant Auger spectra and its evolution as a function of the excitation energy by multimode excitation during the scattering process. As a result, the resonant Auger spectra display two qualitatively different spectral features following the Raman and non-Raman dispersion laws, respectively. Calculations show that two observed thresholds of formation of non-Raman spectral bands are related to the "double-edge" structure of the X-ray absorption spectrum.

  • 46.
    Liu, Jicai
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Nicolas, P
    Morin, V
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO).
    Kosugi, N
    Gelmukhanov, Faris
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Multimode resonant Auger scattering from the ethylene moleculeManuskript (preprint) (Övrigt vetenskapligt)
  • 47.
    Liu, Ji-Cai
    et al.
    North China Elect Power Univ, Dept Math & Phys, Beijing 102206, Peoples R China..
    Savchenko, Viktoriia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Gel'mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Odelius, Michael
    High resolution X-ray spectra of carbon monoxide reveal ultra-fast dynamics induced by long UV pulse2021Ingår i: Artikel i tidskrift (Refereegranskat)
  • 48.
    Liu, Ji-Cai
    et al.
    North China Elect Power Univ, Dept Math & Phys, Beijing 102206, Peoples R China..
    Savchenko, Viktoriia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Int Res Ctr Spect & Quantum Chem IRC SQC, Krasnoyarsk 660041, Russia..
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Int Res Ctr Spect & Quantum Chem IRC SQC, Krasnoyarsk 660041, Russia..
    Gel'mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Int Res Ctr Spect & Quantum Chem IRC SQC, Krasnoyarsk 660041, Russia.;Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    High-resolution x-ray spectra of carbon monoxide reveal ultrafast dynamics induced by long UV pulse2021Ingår i: New Journal of Physics, E-ISSN 1367-2630, Vol. 23, nr 6, artikel-id 063030Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In theoretical simulations of a UV + x-ray pump-probe (UVX-PP) setup, we show that frequency detuning of the pump UV pulse acts as a camera shutter by regulating the duration of the UVX-PP process. This two-photon absorption with long overlapping UV and x-ray pulses, allowing for high spectral resolution, thereby provides information about ultrafast dynamics of the nuclear wave packet without the requirement of ultrashort pulses and controlled delay times. In a case study of carbon monoxide, the calculated UVX-PP spectra of the O1s (-1)2 pi (1) and C1s (-1)2 pi (1) core-excited states show different vibrational profiles. The interference of intermediate vibrational states reveals details of nuclear dynamics in the UVX-PP process related to a variable duration time controlled by the UV detuning. Both O1s (-1)2 pi (1) and C1s (-1)2 pi (1) pump-probe channels display a splitting of the spectral profile, which however is associated with different physical mechanisms. At the O1s (-1)2 pi (1) resonance, the observed dispersive and non-dispersive spectral bands intersect and result in destructive interference.

  • 49.
    Liu, Ji-Cai
    et al.
    North China Elect Power Univ, Dept Math & Phys, Beijing 102206, Peoples R China..
    Savchenko, Viktoriia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Int Res Ctr Spect & Quantum Chem IRC SQC, Krasnoyarsk 660041, Russia..
    Kimberg, Victor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Int Res Ctr Spect & Quantum Chem IRC SQC, Krasnoyarsk 660041, Russia..
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Gel'mukhanov, Faris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Siberian Fed Univ, Int Res Ctr Spect & Quantum Chem IRC SQC, Krasnoyarsk 660041, Russia.;Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Polarization-sensitive IR-pump-x-ray-probe spectroscopy2021Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 103, nr 2, artikel-id 022829Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    X-ray absorption and core-ionization spectra of molecules pumped by two coherent infrared pulses with different polarizations are studied theoretically. We have found a sensitivity of the vibrational profile of x-ray probe spectra to polarizations of the IR and x-ray pulses. This polarization dependence is qualitatively different for x-ray absorption and x-ray photoelectron spectra. Measurements of this polarization dependence allow to select the difference in Franck-Condon distributions from the lowest and pumped vibrational levels of the electronic ground state. The proposed technique is exemplified numerically using x-ray absorption spectra of the pumped CO molecule. We also show that this kind of pump-probe spectroscopy can enable studies of the dynamics of molecular rotation.

  • 50.
    Liu, Jicai
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Travnikova, O
    Lindblad, A
    Nicolas, C
    Söderström, J
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO).
    Ultrafast dissociation of core-excited SF6 probed by Auger-Doppler e_ect in the _eld of circularly polarized X-raysManuskript (preprint) (Övrigt vetenskapligt)
12 1 - 50 av 89
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