Conformer- and Mode-Specific Excited State Lifetimes of Cold Protonated Tyrosine Ions.
The excited state lifetimes of conformer- and mode-selected cold protonated tyrosine have been measured for the first time through a picosecond pump-probe photodissociation scheme. Whereas the photofragmentation mechanism of protonated tyrosine ions strongly depends upon the interaction of the carboxylic acid group with the phenol ring, their excited state lifetimes are quite similar and decrease as the excess energy increases from 1.5 ns at the band origin to 900 ps and less than 500 ps for the 10(1) and 10(2) bands, respectively. Surprisingly, the excited state lifetime of the conformer with the anti orientation of the hydroxyl oxygen lone pair with respect to the ammonium group dramatically increases as compared to the others conformers up to 10 ns at the band origin and by more than a factor of 2 for the 10(1) band. The present experimental results clearly emphasize the subtle effect of the structural conformation on the excited state properties of molecular ions.
†CNRS, Université Paris Sud, Institut des Sciences Moléculaires d'Orsay (ISMO) UMR 8624, 91405 Orsay Cedex, France.
Satchin
S
Soorkia
†CNRS, Université Paris Sud, Institut des Sciences Moléculaires d'Orsay (ISMO) UMR 8624, 91405 Orsay Cedex, France.|‡Université Paris Sud, CLUPS (Centre Laser de l'Université Paris Sud) LUMAT FR 2764, 91405 Orsay Cedex, France.
Michel
M
Broquier
§CNRS, Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, UMR 7538, F-93430 Villetaneuse, France.
Gilles
G
Grégoire
Photochemistry and Excited State; Spectroscopy