Conformer- and Mode-Specific Excited State Lifetimes of Cold Protonated Tyrosine Ions
Satchin Soorkia1, Michel Broquier1,2, Gilles Grégoire3
1†CNRS, Université Paris Sud, Institut des Sciences Moléculaires d'Orsay (ISMO) UMR 8624, 91405 Orsay Cedex, France.
Abstract:
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.
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