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  • 1.
    Lin, Li-Li
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Wang, Chuan-Kui
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Inelastic Electron Tunneling Spectroscopy of Gold-Benzenedithiol-Gold Junctions: Accurate Determination of Molecular Conformation2011In: ACS NANO, ISSN 1936-0851, Vol. 5, no 3, p. 2257-2263Article in journal (Refereed)
    Abstract [en]

    The gold benzenedithiol gold junction is the classic prototype of molecular electronics. However, even with the similar experimental setup, it has been difficult to reproduce the measured results because of the lack of basic information about the molecular confirmation inside the junction. We have performed systematic first principles study on the inelastic electron tunneling spectroscopy of this classic junction. By comparing the calculated spectra with four different experimental results, the most possible conformations of the molecule under different experimental conditions have been successfully determined. The relationship between the contact configuration, and the resulted spectra is revealed. It demonstrates, again that one should always combine the theoretical and experimental inelastic electron tunneling spectra to determine the molecular conformation in a junction. Our simulations have also suggested that in terms of the reproducibility and stability, the electromigrated nanogap technique is much better than the mechanically controllable break junction technique.

  • 2.
    Liu, Ji-Cai
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Felicissimo, Viviane Costa
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Guimarães, Freddy Fernandes
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Wang, Chuankui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Gelmukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Coherent control of population and pulse propagation beyond the rotating wave approximation2008In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 41, no 7, article id 074016Article in journal (Refereed)
    Abstract [en]

    The dynamics of populations of the vibrational states in a NO molecule ( one-photon absorption) and of the electronic states in a 4,4'-bis( dimethylamino) stilbene molecule ( two-photon absorption) is studied versus the frequency, intensity and shape of the laser pulse. We show that specially designed infrared laser pulses can build selective populations of certain vibrational states. A detuning of light frequency from the vibrational resonance qualitatively changes the dynamics of populations. It is found out that the populations of the nonresonant levels follow the pulse shape adiabatically if the detuning significantly exceeds the inverse characteristic time of the change of the pulse. Depopulation of the nonresonant vibrational states leads to a high population of the resonant state at the end of the pulse. Complete breakdown of the standard rotating wave approximation for a two-photon absorption process is observed even for a rather small intensity of the laser pulse. An analytical solution for the interaction of a pulse with a three-level system beyond the rotating wave approximation is obtained, and it is in close agreement with the strict numerical solution of the amplitude equations. Special attention is paid to the population dynamics of randomly oriented molecules. The orientational disorder as well as the vibrations limit the coherent population transfer. Calculations show the strong role of the anisotropy of photoexcitation in the coherent control of populations which can affect the anisotropy of photobleaching.

  • 3.
    Liu, Ji-Cai
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Gelmukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Wang, Chuan-Kui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Dynamics of cooperative emissions in a cascade three-level molecular system driven by an ultrashort laser pulse2008In: Chinese Physics (Beijing), ISSN 1009-1963, E-ISSN 1741-4199, Vol. 17, no 11, p. 4211-4217Article in journal (Refereed)
    Abstract [en]

    This paper investigates the dynamics of cooperative emissions in a cascade three-level system driven by an ultras short laser pulse by solving numerically the full-wave Maxwell-Bloch equations. The 4, 40-bis(dimethylamino) stilbene molecule is used as the model molecule because of its strong two-photon absorption property. The two-colour cooperative emissions are studied as functions of molecular number density and dephasing rate of the dipole coherence. The propagation effects on the evolution of the cooperative radiations are also taken into account. The cooperative radiations are enhanced for large number density of the molecule, while the fast dephasing of the dipole coherence reduces the intensity of the cooperative radiations and delays the emission times or even inhibits the formation of the emissions. The delay time of the radiation decreases with the increase of the molecular number density and the propagation distance.

  • 4.
    Liu, Jicai
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Sun, Yu-Ping
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Wang, Chuankui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Gelmukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Auger effect in the presence of strong x-ray pulses2010In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, ISSN 1050-2947, Vol. 81, no 4, p. 043412-Article in journal (Refereed)
    Abstract [en]

    We study the role of propagation of strong x-ray free-electron laser pulses on the Auger effect. When the system is exposed to a strong x-ray pulse the stimulated emission starts to compete with the Auger decay. As an illustration we present numerical results for Ar gas with the frequency of the incident x-ray pulse tuned in the 2p(3/2)-4s resonance. It is shown that the pulse propagation is accompanied by two channels of amplified spontaneous emission, 4s-2p(3/2) and 3s-2p(3/2), which reshape the pulse when the system is inverted. The population inversion is quenched for longer propagation distances where lasing without inversion enhances the Stokes component. The results of simulations show that the propagation of the strong x-ray pulses affect intensively the Auger branching ratio.

  • 5.
    Liu, Ji-Cai
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Wang, Chuan-Kui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Gelmukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Dynamics of multilevel molecules and pulse propagation beyond rotating wave approximation near two-photon resonance2007In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 76, no 4, article id 043422Article in journal (Refereed)
    Abstract [en]

    Dynamics of multilevel molecules and pulse propagation is studied near the two-photon resonance. We have found a strict solution of this problem beyond the rotating wave approximation. Our analytical solution is in close agreement with the strict numerical solution for the 4,4(')-bis(dimethylamino) stilbene molecule. The compensation of the dynamical Stark shift is studied for fixed-in-space molecules. It is shown that the orientational disorder does not allow complete compensation of the dynamical Stark shift.

  • 6.
    Liu, Ji-Cai
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Wang, Chuan-Kui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Gelmukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Optical limiting of short laser pulses2007In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 76, no 053804Article in journal (Refereed)
    Abstract [en]

    The dynamics of pulse propagation accompanied by harmonic generation, stimulated Raman scattering, amplified spontaneous emission, and superfluorescence is studied near the two-photon resonance. We explore the optical limiting of intense and short laser pulses. The numerical solutions of the coupled Bloch and Maxwell's equations for the 4,4(')-bis(dimethylamino) stilbene molecule are compared with the two-photon area theorem. It is shown that the area theorem explains qualitatively the major dynamical properties of pulse propagation even if the propagation is accompanied by the generation of new fields. In agreement with the area theorem, we see that the conventional dependence of the transmittance on the propagation depth is not valid for intense pulses.

  • 7.
    Minaev, Boris
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Wang, Yanhua
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Wang, Chuankui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Density functional theory study of vibronic structure of the first absorption Qx band in free-base porphin2006In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 65, no 2, p. 308-323Article in journal (Refereed)
    Abstract [en]

    Harmonic vibrational frequencies and vibronic intensities in the first S-0 -> S-1 (pi pi*) absorption band of free-base porphin (H2P) are investigated by hybrid density functional theory (DFT) with the standard B3LYP functional. The S-0-S-1 transition probability is calculated using time-dependent DFT with account of Franck-Condon (FC) and Herzberg-Teller (HT) contributions to the electric-dipole transition moments including displacements along all 108 vibrational modes. Two weak wide bands observed in the gas phase absorption spectra of the H2P molecule at 626 and 576 nm are interpreted as the 0-0 band of the X(1)A(g)-> B-3u transition and the 0-1 band with largest contributions from the nu(10)(a(g)) = 1610 cm(-1) and nu(19)(b(1g)) = 1600 cm(-1) modes, respectively, in agreement with previous tentative assignments. Both bands are induced by the HT mechanism, while the FC contributions are negligible. A number of fine structure bands, including combination of two vibrational quanta, are obtained and compared with available spectra from supersonic jet and Shpolskij matrices. Both absorption and fluorescence spectra are interpreted on ground of the linear coupling model and a good fulfillment of the mirror-symmetry rule.

  • 8. Sun, Y. H.
    et al.
    Zhao, K.
    Wang, Chuankui
    KTH, Superseded Departments, Biotechnology.
    Luo, Yi
    KTH, Superseded Departments, Biotechnology.
    Ren, Y.
    Tao, X. T.
    Jiang, M. H.
    Two-photon absorption properties of multi-branched bis-(styryl)benzene based organic chromophores2004In: Journal of Molecular Structure: THEOCHEM, ISSN 0166-1280, Vol. 682, no 03-jan, p. 185-189Article in journal (Refereed)
    Abstract [en]

    Two-photon absorption (TPA) cross-sections of a series of multi-branched trans-stilbene charge transfer compounds with benzene as the coupling center have been theoretically investigated using analytical response theory at the random phase approximation level. It shows that the TPA cross-sections of compounds with a quasi-one-dimensional geometrical arrangement can be enhanced through the pure electronic coupling of different branches. The effects of different combination of donor/acceptor substitutions on the TPA cross-sections have also been discussed.

  • 9. Sun, Y. H.
    et al.
    Zhao, K.
    Wang, Chuankui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Luo, Yi
    KTH, Superseded Departments, Biotechnology.
    Yan, Y. X.
    Tao, X. T.
    Jiang, M. H.
    Theoretical studies on nonlinear optical properties of two newly synthesized compounds: PVPHC and DPVPA2004In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 394, no 03-jan, p. 176-181Article in journal (Refereed)
    Abstract [en]

    The nonlinear optical properties of two newly synthesized molecules 9-(4-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-phenyl)-9H-carbazole (PVPHC) and diphenyl-(4-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-phenyl)-amine (DPVPA) have been studied using hybrid density functional theory at B3LYP level. A few-state model, as well as response theory, have been employed to calculate their two-photon absorption cross-sections. The theoretical results are in good agreement with the experimental measurements available. It is found that the maximal two-photon absorption cross-sections of these compounds can be well described by a three-state model and both compounds have large two-photon absorption cross-section in optical regime. Strong charge-transfer process upon excitation has been revealed, indicating that these two compounds are good candidates as two-photon polymerization initiators.

  • 10.
    Sun, Yuping
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Gavrilyuk, Sergey
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Liu, Jicai
    KTH, School of Biotechnology (BIO).
    Wang, C.K.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Gelmukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Optical limiting and pulse reshaping of picosecond pulse trains by fullerene C602009In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 174, p. 125-130Article in journal (Refereed)
    Abstract [en]

    We present a dynamical theory of nonlinear absorption and propagation of a laser pulse train that contains 20 subpulses with an individual pulse width of loops. It is shown that the accumulative nonlinearity and the reverse saturation absorption play important roles in the optical limiting performance and pulse shaping. When the incident field is not too strong, the population transfer reveals a slow response process, and the periodic sequence of short light pulses can be regarded as a continuous long pulse. The general theory is applied to fullerence C-60, which is a popular reverse saturable absorption material and a good limiter because of its larger excited-state absorption cross-section compared with that of the ground state. The propagation of the front subpulses is mainly affected by the linear transition between the ground state and the first excited singlet state, while the latter subpulses are attenuated by the excited-state absorption. Moreover, these two different kinds of absorption mechanisms result in different radial distributions for different subpulses. The pulse propagation is studied by solving numerically the coupled rate equations and the propagation equation of the optical pulse intensity, using experimental parameters as input. We suggest a new method to measure the lifetime of the triplet state.

  • 11.
    Sun, Yu-Ping
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Liu, Ji-Cai
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Wang, Chuan-Kui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Gel'mukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Propagation of a strong x-ray pulse: Pulse compression, stimulated Raman scattering, amplified spontaneous emission, lasing without inversion, and four-wave mixing2010In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 81, no 1Article in journal (Refereed)
    Abstract [en]

    We study the compression of strong x-ray pulses from x-ray free-electron lasers (XFELs) propagating through the resonant medium of atomic argon. The simulations are based on the three-level model with the frequency of the incident x-ray pulse tuned in the 2p(3/2)-4s resonance. The pulse propagation is accompanied by the self-seeded stimulated resonant Raman scattering (SRRS). The SRRS starts from two channels of amplified spontaneous emission (ASE), 4s-2p(3/2) and 3s-2p(3/2), which form the extensive ringing pattern and widen the power spectrum. The produced seed field triggers the Stokes ASE channel 3s-2p(3/2). The population inversion is quenched for longer propagation distances where the ASE is followed by the lasing without inversion (LWI), which amplifies the Stokes component. Both ASE and LWI reshape the input pulse: The compressed front part of the pulse (up to 100 as) is followed by the long tail of the ringing and beating between the pump and Stokes frequencies. The pump pulse also generates weaker Stokes and anti-Stokes fields caused by four-wave mixing. These four spectral bands have fine structures caused by the dynamical Stark effect. A slowdown of the XFEL pulse up to 78% of the speed of light in vacuum is found because of a large nonlinear refractive index.

  • 12.
    Sun, Yu-Ping
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Rinkevicius, Zilvinas
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Wang, Chuan-Kui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Carniato, Stephane
    Simon, Marc
    Taieb, Richard
    Gel'mukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Two-photon-induced x-ray emission in neon atoms2010In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 82, no 4, p. 043430-Article in journal (Refereed)
    Abstract [en]

    We investigated the resonant x-ray emission from a neon atom induced by the two-photon population of a double-core-hole excited state. Two qualitatively different schemes of this process are studied: The first one involves an off-resonant intermediate single-core-hole state; the second scheme passes through a resonant core-ionized intermediate state. The numerical simulations of the resonant x-ray emission performed for different peak intensities and pulse durations show significant population of the double-core-hole final states. Therefore, rather strong two-photon absorption-induced x-ray emission is predicted for both studied schemes. Thus, high counting rates in experimental measurements are expected.

  • 13.
    Sun, Yuping
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Wang, Chuankui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Gel'mukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Rotational Doppler effect in x-ray photoionization2010In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 82, no 5, p. 052506-Article in journal (Refereed)
    Abstract [en]

    The energy of the photoelectron experiences a red or blue Doppler shift when the molecule recedes from the detector or approaches him. This results in a broadening of the photoelectron line due to the translational thermal motion. However, the molecules also have rotational degrees of freedom and we show that the translational Doppler effect has its rotational counterpart. This rotational Doppler effect leads to an additional broadening of the spectral line of the same magnitude as the Doppler broadening caused by translational thermal motion. The rotational Doppler broadening as well as the rotational recoil broadening is sensitive to the molecular orbital from which the photoelectron is ejected. This broadening should be taken into account in analysis of x-ray photoemission spectra of super-high resolution and it can be directly observed using x-ray pump-probe spectroscopy.

  • 14. Tian, Yu-Peng
    et al.
    Li, Lin
    Zhang, Ju-Zhou
    Yang, Jia-Xiang
    Zhou, Hong-Ping
    Wu, Jie-Ying
    Sun, Ping-Ping
    Tao, Li-Min
    Guo, Ya-Hui
    Wang, Chuan-Kui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Xing, Hui
    Huang, Wen-Hao
    Tao, Xu-Tang
    Jiang, Min-Hua
    Investigations and facile synthesis of a series of novel multi-functional two-photon absorption materials2007In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 17, no 34, p. 3646-3654Article in journal (Refereed)
    Abstract [en]

    Six centrosymmetric D-(pi-A)(3) structural triphenylamine derivatives that can be used as two- photon photopolymerization and optical data storage chromophores, tris[ 4-( 4- pyridylethenyl) phenyl] amine ( 1), tris[ 4-( 2- pyridylethenyl) phenyl] amine ( 2), tris( 4- cyanoethenylphenyl) amine ( 3), tris[ 4- butylacrylatephenyl] amine ( 4), tris[ 4- methylacrylatephenyl] amine ( 5) and tris[ 4- acrylicethenylphenyl] amine ( 6), have been successfully synthesized via a triple palladium-catalyzed Heck coupling reaction, and the novel chromophores were fully characterized by elemental analysis, IR, (1)H-NMR and ESIMS. The structure for 3 was determined by single crystal X-ray diffraction study. One- and two-photon absorption and fluorescence in various solvents were experimentally investigated. Two-photon initiated polymerization microfabrication and optical data recording experiments were carried out under 780 nm laser radiation, and the possible polymerization mechanism is discussed based on theoretical calculations. All the six chromophores have relatively large two-photon absorption crosssections, and exhibit optical memory and highly efficient two-photon initiated polymerization abilities.

  • 15.
    Velkov, Yasen
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Liu, Ji-Cai
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Wang, Chuan-Kui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Gel'mukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    X-ray absorption of N2 accompanied by infrared-induced transitions between the ungerade and gerade core levels2008In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 41, no 14, p. 145601-Article in journal (Refereed)
    Abstract [en]

    We study a two-colour pump–probe scheme of x-ray absorption accompanied by core-hole hopping in the field of a strong IR laser. The process is exemplified for fixed-in-space and randomly oriented homonuclear diatomic molecules N2 near the 1σu → 1πg x-ray absorption transition. The laser field mixes the core holes of opposite parities and causes Rabi splitting of the core-excited states. The IR field results in spectral broadening and shifts of the x-ray resonances as well as decrease of x-ray photoabsorption. The Stark broadening of the x-ray absorption spectrum depends on the orientation of the molecule and the angle between the polarization vectors of the x-ray and IR fields. The spectral changes caused by the IR field are weaker for randomly oriented molecules in comparison with fixed-in-space molecules.

  • 16.
    Wang, Chuankui
    et al.
    KTH, Superseded Departments, Biotechnology.
    Wang, Yanhua
    KTH, Superseded Departments, Biotechnology.
    Su, Y.
    Department of Physics, Shandong Normal University, Jinan.
    Luo, Yi
    KTH, Superseded Departments, Biotechnology.
    Solvent dependence of solvatochromic shifts and the first hyperpolarizability of para-nitroaniline: a nonmonotonic behaviour2003In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 119, no 8, p. 4409-Article in journal (Refereed)
    Abstract [en]

    Solvent dependence of the electronic structure and nonlinear optical properties of the para-nitroaniline (pNA) molecule on the polarity of the solutions has been studied using the polarizable continuum model in combination with the hybrid density functional theory. With a supermolecular approach, specific hydrogen bonding effects have also been fully considered. Good agreement between theory and experiments are obtained for both solvatochromic shifts of the charge transfer state and the solvent-induced first hyperpolarizability of pNA.

  • 17.
    Wang, Yanhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Halik, M.
    Department of Chemistry, University of Arizona.
    Wang, Chuankui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Marder, S. R.
    Department of Chemistry, University of Arizona.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Solvent effects on the vibronic one-photon absorption profiles of dioxaborine heterocycles2005In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 123, no 19, p. 194311-1-194311-7Article in journal (Refereed)
    Abstract [en]

    The vibronic profiles of one-photon absorption spectra of dioxaborine heterocycles in gas phase and solution have been calculated at the Hartree-Fock and density-functional-theory levels. The polarizable continuum model has been applied to simulate the solvent effect, while the linear coupling model is used to compute the Franck-Condon and Herzberg-Teller contributions. It is found that a good agreement between theory and experiment can be achieved when the solvent effect and electron correlation are taken into account simultaneously. For the first excited charge-transfer state, the maximum of its Herzberg-Teller profile is blueshifted from that of the Franck-Condon profile. The shifted energy is found to be around 0.2 eV, which agrees well with the measured energy difference between two- and one-photon absorptions of the first excited state.

  • 18.
    Wang, Yanhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Wang, Chuankui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Vibrational contributions to nonlinear optical properties of methanol, ethanol and propanol2005In: Journal of Molecular Structure: THEOCHEM, ISSN 0166-1280, Vol. 717, no 1-3, p. 223-230Article in journal (Refereed)
    Abstract [en]

    Static and dynamic vibrational contributions to the linear polarizability and the first and second nonlinear hyperpolarizabilities of methanol, ethanol and propanol have been calculated. Both the pure vibrational contribution and the zero-point vibrational averaging contribution have been determined by adopting the perturbation treatment of Bishop and Kirtman at the Hartree-Fock level. The pure vibrational contribution is quite important at the static limit, while in the optical region it varies for different nonlinear optical processes. The zero-point vibrational averaging contribution is a quite large correction to the electronic nonlinear optical (NLO) properties, especially for the second hyperpolarizability at finite fundamental frequencies. Vibrational analysis shows that the swinging modes at around 300 cm(-1) and the C-H stretching modes at around 3160 cm(-1) often give large contributions.

  • 19. Yang, Jia-Xiang
    et al.
    Li, Lin
    Wang, Cai-Xia
    Tian, Yu-Peng
    Wu, Fei
    Xing, Xiao-Juan
    Wang, Chuan-Kui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Tang, Huo-Hong
    Huang, Wen-Hao
    Tao, Xu-Tang
    Jiang, Min-Hua
    Facile synthesis, optical properties and theoretical calculation of two novel two-photon absorption chromophores2010In: Journal of Luminescence, ISSN 0022-2313, E-ISSN 1872-7883, Vol. 130, no 4, p. 654-659Article in journal (Refereed)
    Abstract [en]

    Two heterocycle-based derivatives that can be used as two-photon absorption chromophore, 9-butyl-3-(2,6-diphenylpyridin-4-yl)-9H-carbazole (BDPYC) and 9-butyl-3-(4-(2, 6-diphenylpyridin-4-yl)styryl)-9H-carbazole (BDPSC) have been successfully synthesized and fully characterized by elemental analysis, IR, H-1 NMR, C-13 NMR and MS. The molecules possess D-pi-A structures, but have different pi bridge. The 9-butylcarbazole is used as a donor (D), and the pyridine ring is used as an acceptor (A). One- and two-photon absorption and excited fluorescence properties in various solvents were experimentally investigated. Two-photon initiated optical data recording experiments have been carried Out under 740 nm laser radiation, and the possible mechanism of optical data storage is discussed based on theoretical calculations.

  • 20.
    Zhao, Ke
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Liu, Ji-Cai
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Wang, Chuan-Kui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Modulation of supercontinuum generation and formation of an attosecond pulse from a generalized two-level medium2007In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 40, p. 1523-1534Article in journal (Refereed)
    Abstract [en]

    The propagation of ultrashort pulses in a generalized two- level system, consisting of permanent dipole moments, is simulated by solving the full Maxwell - Bloch equations. Special attention has been paid to the supercontinuum generation of spectra and the formation of attosecond ( as) pulses. It is found that the supercontinuum generation is strongly modulated by both area and width of the pulse, resulting from the interference between the splitting pulses in the time domain and the implication of the time - energy uncertainty relation. The effect of the permanent dipole moment on the supercontinuum generation is discussed in detail. Calculations show that a well- shaped 132 as pulse can be generated from a 2 fs incoming pulse under the condition where the permanent dipole moment difference between two levels is equal to the transition dipole moment between them. Influences of carrier- envelope phase and time- dependent ionization on the spectral and temporal evolution of the ultrashort pulses are also discussed at length.

  • 21.
    Zhao, Ke
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Wang, Chuan-Kui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Luo, Yi
    Shandong Normal Univ, Coll Phys & Elect, Jinan.
    Two-photon absorbation activities of interating dipolar chromophores: a DFT study.Manuscript (preprint) (Other academic)
1 - 21 of 21
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