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The npσ,π to EF emission systems in D2 studied by selective excitation
KTH, School of Engineering Sciences (SCI), Physics, Atomic and Molecular Physics.
KTH, School of Engineering Sciences (SCI), Physics, Atomic and Molecular Physics.
KTH, School of Engineering Sciences (SCI), Physics, Atomic and Molecular Physics.
KTH, School of Engineering Sciences (SCI), Physics, Atomic and Molecular Physics.
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2005 (English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 38, no 6, 659-664 p.Article in journal (Refereed) Published
Abstract [en]

The np sigma 1 Sigma(u)(+) and np pi (1)Pi(u) states in D-2 have been selectively excited using monoenergetic synchrotron light in the range of 13.97-15.84 eV and the subsequent dispersed emission to the EF (1)Sigma(g)(+) state was observed using a grating spectrometer. In total, 18 emission bands from the levels n = 3-6 were studied and rotationally analysed. The intensities of the P and R branches relative to the Q branch were found to vary strongly in the np pi (1)Pi(u)(+)-EF(1)Sigma(g)(+) bands indicating the existence of predissociations of np pi (1)Pi(u)(+) levels above the dissociation limit D(1s) + D(2l).

Place, publisher, year, edition, pages
2005. Vol. 38, no 6, 659-664 p.
Keyword [en]
Absorption spectroscopy, Dispersion (waves), Dissociation, Electric excitation, Electron energy levels, Synchrotron radiation, Dispersed emissions, Emission bands, Grating spectrometers, Molecular hydrogen
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-7997DOI: 10.1088/0953-4075/38/6/004ISI: 000228455000008Scopus ID: 2-s2.0-16244367150OAI: oai:DiVA.org:kth-7997DiVA: diva2:13199
Note
QC 20100916Available from: 2008-02-20 Created: 2008-02-20 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Flourescence properties of trendy molecules studied with synchrotron radiation
Open this publication in new window or tab >>Flourescence properties of trendy molecules studied with synchrotron radiation
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis summarises the experimental results on molecular spectroscopy of gas phase molecules using synchrotron radiation in the UV- VUV and soft-X rays regions. The results of applying Photon Induced Fluorescence Spectroscopy (PIFS) to D2, H2S, H2O and pyrimidine are presented and discussed. Both inner and outer shell excitations of free molecules lead to different relaxation processes. However, a common result is that when the molecule breaks and the resulting neutral fragments are left in an excited state, they might fluoresce in the UV- Vis range. PIFS technique has two main advantages, it permits to detect neutral fragments and to identify the fluorescing species. From this fact, we can infer dissociation channels and trace back the electronic processes that led to the fluorescence. For these molecules we have analysed and interpreted both dispersed and undispersed fluorescence. What motivates our work is the lack of fluorescence studies and in a more general sense, to contribute to the knowledge of important molecules for life such as water and pyrimidine.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. ix, 47 p.
Series
Trita-FYS, ISSN 0280-316X ; 2006.57
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-4148 (URN)91-7178-428-4 (ISBN)
Presentation
2006-10-09, Sal FA31, AlbaNova universitetscentrum, Roslagstullsb 21, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101125Available from: 2006-10-13 Created: 2006-10-13 Last updated: 2010-11-25Bibliographically approved
2. Visible spectroscopy as a sensitive diagnostic tool for fusion plasmas
Open this publication in new window or tab >>Visible spectroscopy as a sensitive diagnostic tool for fusion plasmas
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

To further the understanding and knowledge about fusion plasmas and their behaviour during different conditions, it is important to be able to collect information about the plasma and the processes occurring within it. Visible spectroscopy, or the study of the visible wavelength light emitted by the plasma, is a useful tool in this search for knowledge.

This thesis is based on experiments where visible wavelength light has been measured and analysed in order to determine quantities about the emitting source. Doppler shift measurements of spectral lines have been utilised to determine the toroidal rotation velocities of plasma impurity ions and to study the correlation with mode rotation and the effect of active feedback control of the resistive wall modes. Information on the impurities present in the plasma has been determined and the calibrated intensities of spectral lines has yielded impurity concentrations, particle fluxes and electron temperature and densities. Ion temperatures have been determined from Doppler broadening measurements.

The measured vibrational and rotational band structure of deuterium molecular spectra has been analysed in order to calculate rotational and vibrational temperatures, relative populations and molecular particle fluxes. The effect of the molecular flux on simple calculations of atomic flux has also been studied. Specific molecular states and transitions of deuterium have also been probed with synchrotron radiation to study the level and transition energies.

The measurement and analysis of visible wavelength light has been demonstrated to be a sensitive diagnostic tool in the quest for increased knowledge about fusion plasmas and molecular structure.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 29 p.
Series
Trita-FYS, ISSN 0280-316X ; 2005:64
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-572 (URN)91-7178-222-2 (ISBN)
Presentation
2005-12-06, Sal FA31, AlbaNova, Roslagstullsbacken 21, Stockholm, 10:15 (English)
Opponent
Supervisors
Note
QC 20101215Available from: 2005-12-23 Created: 2005-12-23 Last updated: 2010-12-15Bibliographically approved
3. Synchrotron radiation studies of gas phase molecules: from hydrogen to DNA sugars
Open this publication in new window or tab >>Synchrotron radiation studies of gas phase molecules: from hydrogen to DNA sugars
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis summarises experimental results on the molecular spectroscopy of gas phase molecules excited by synchrotron radiation in the VUV and soft X-ray regions. We have used three different detection techniques, photon induced fluorescence spectroscopy, photoionisation mass spectroscopy and near edge X-ray absorption fine structure spectroscopy to study molecular deuterium, hydrogen sulphide, ammonia, methanol, pyridine, pyridazine, pyrimidine, pyrazine, s-triazine, and 2-deoxy-D-ribose, the last one also known as the DNA sugar. Out of this variety of techniques and molecules we have shown that: (1) high resolution dispersed fluorescence allows us to identify vibrational and rotational bands in molecular deuterium, as well as to estimate the predissociation probability of the same molecule [paper I]; (2) the main species fluorescing after core excitation of methane, ammonia [paper III], hydrogen sulphide [paper II], pyridine, pyrimidine and s-triazine is H Balmer α, followed by fluorescence from ionised species, molecular bands and Balmer β, γ , δ; (3) the Rydberg enhancement seen in fluorescence measurements of water [Melero et al. PRL 96 (2006) 063003], corroborated later in H2S [paper II], NH3 [paper III] and CH4 [paper III] and postulated as general behaviour for molecules formed by low-Z atoms, is also seen in larger organic cyclic molecules, e.g. azabenzenes; (4) when dissociative ionisation of pyridine, pyridazine, pyrimidine, pyrazine, s-triazine and 2-deoxy-D-ribose occurs, concerted bond rearrangement and nuclear motion takes place as opposed to stepwise dissociation [papers V and VI].

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. x, 56 p.
Series
Trita-FYS, ISSN 0280-316X ; 2008:1
Keyword
KTH thesis, synchrotron radiation, gas phase, bio molecules
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-4640 (URN)978-91-7178-852-8 (ISBN)
Public defence
2008-03-13, FA31, Albanova, Roslagstullabacken 21, Stockholm, 10:15
Opponent
Supervisors
Note
QC 20100916Available from: 2008-02-20 Created: 2008-02-20 Last updated: 2010-09-16Bibliographically approved

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