Externally funded project

Lifetime and electronic state interference and ultrafast dissociation of inner-shell resonant Raman excited CO, NO, CO2, and N2O investigated by photon-induced fragment-fluorescence spectrometry (PIFS). (lifetime and ESI in ultrafast dissociation)

Project Details
Project duration: 05/200801/2013


Inner-shell resonance
decay processes of molecules after their excitation by synchrotron radiation
(electron emission processes, like Auger/ double Auger decays or ultrafast
dissociative processes, like Coulomb explosion) are prototypes for the test of
basic quantum mechanics and are, therefore, the topic of intense current
research. In the present project two aspects of these decay processes will be
investigated in a fresh experimental approach, where excitation by small
bandwidth monochromatized synchrotron radiation is used together with high
resolution (dispersed) fragment fluorescence spectrometry and polarimetry
(photon-induced fluorescence spectrometry, PIFS) to determine absolute
fragment-state selective fragmentation cross sections as functions of the
exciting-photon energy: 1) Lifetime vibrational interference (LVI) and
electronic state interference (ESI) effects, and 2) ultrafast dissociation.
This as yet very scarcely applied experimental approach will be combined with
elaborate ab-initio calculations by a co-operating group for a quantitative
comparison between experiment and theory. The decays of molecular inner shell
resonances are strongly influenced by lifetime vibrational interference (LVI)
and electronic state interference (ESI), due to closely neighbouring vibronic
or electronic resonant states, overlapping partly within their natural
linewidths. PIFS experiments, partly with polarization analysis of the emitted
fluorescence, will be used to investigate experimentally LVI and ESI in the
inner-shell resonantly excited heteroatomic molecules CO and NO. For these
molecules it is possible to compare the decay of inner shell resonances
strongly influenced by LVI and ESI effects (excitation of the O 1s electron)
with the decay of resonances weaker influenced (excitation of the C 1s or N 1s
electron in CO or NO, respectively). Ultrafast dissociation processes of the
inner-shell resonances will be investigated by dispersively monitoring the
fluorescence emission of excited neutral fragments. These fragments cannot be
emitted by the Coulomb explosion mechanism and are an indication of a very fast
dissociation process competing with the abundant autoionization mechanisms for
the deexcitation of the resonances. Finally, we will start to investigate
fragmentation processes of the triatomic molecules CO2 and N2O
after vibration-state selective inner-shell excitation of the C1s (N1s) and O1s
electrons into molecular excited CO+ (N2+ and
NO+) fragments by recording dispersedly CO+ (N2+
and NO+) fluorescence in well-known wavelength ranges, being
therefore state-selective to the CO+ (N2+ and
NO+) fragment state.

Principal Investigator

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Last updated on 2019-17-07 at 14:54