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Coherent Oscillation and Ultrafast Internal Conversion of Tetrafluoroethene after Excitation at 197 nm
Author(s) -
Trushin Sergei A.,
Sorgues Sébastien,
Fuß Werner,
Schmid Wolfram E.
Publication year - 2004
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200400218
Subject(s) - excited state , conical intersection , chemistry , overtone , atomic physics , photoionization , rydberg state , excitation , dissociation (chemistry) , ground state , photodissociation , molecular physics , rydberg formula , ionization , physics , photochemistry , spectral line , ion , organic chemistry , quantum mechanics , astronomy
C 2 F 4 was excited by using a 150 fs pulse in its longest‐wavelength band to the Rydberg (3 s) state and then probed by photoionization techniques at 810 nm. The molecule relaxes in two consecutive steps (time constants 29 and 118 fs), probably via the ππ* state, which is lowered in energy by stretching and twisting the CC bond. A coherent oscillation (350 fs) was found, which we assign to an overtone of the twist vibration (47.6 cm −1 ) in this state. We also conclude that dissociation to singlet and some triplet CF 2 only takes place in the hot ground state of C 2 F 4 , from where also the C 2 F 4 triplet state is populated. The potentials and their conical intersections are discussed with respect to relaxation and dissociation, including also some new considerations of thermal processes.