title: Excited State Dynamics of Protonated Phenylalanine and Tyrosine: Photo-Induced Reactions Following Electronic Excitation.
abstract: The electronic spectroscopy and the electronic excited state properties of cold protonated phenylalanine and protonated tyrosine have been revisited on a large spectral domain and interpreted by comparison with ab initio calculations. The protonated species are stored in a cryogenically cooled Paul trap, maintained at ∼10 K, and the parent and all the photofragment ions are mass-analyzed in a time-of-flight mass spectrometer, which allows detecting the ionic species with an improved mass resolution compared to what is routinely achieved with a quadrupole mass spectrometer. These new results emphasize the competition around the band origin between two proton transfer reactions from the ammonium group toward either the aromatic chromophore or the carboxylic acid group. These reactions are initiated by the coupling of the locally excited ππ* state with higher charge transfer states, the positions and coupling of which depend on the conformation of the protonated molecules. Each of these reaction processes gives rise to specific fragmentation channels that supports the conformer selectivity observed in the photofragmentation spectra of protonated tyrosine and phenylalanine.
authors.affiliation: †CNRS, Laboratoire de Physique des Interactions Ioniques et Moléculaires (PIIM) UMR 7345, Aix Marseille Université, 13397 Marseille cedex 20, France.
authors.forename: Géraldine
authors.initials: G
authors.lastname: Féraud
authors.affiliation: ‡CLUPS (Centre Laser de l'Université Paris Sud) LUMAT FR 2764, Université Paris Sud, 91405 Orsay Cedex, France.|§CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO) UMR 8624, Université Paris Sud, 91405 Orsay Cedex, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Broquier
authors.affiliation: †CNRS, Laboratoire de Physique des Interactions Ioniques et Moléculaires (PIIM) UMR 7345, Aix Marseille Université, 13397 Marseille cedex 20, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Dedonder
authors.affiliation: †CNRS, Laboratoire de Physique des Interactions Ioniques et Moléculaires (PIIM) UMR 7345, Aix Marseille Université, 13397 Marseille cedex 20, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Jouvet
authors.affiliation: ∥CNRS, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, UMR 7538, Université Paris 13, 93430 Villetaneuse, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Grégoire
authors.affiliation: §CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO) UMR 8624, Université Paris Sud, 91405 Orsay Cedex, France.
authors.forename: Satchin
authors.initials: S
authors.lastname: Soorkia
mesh_terms: D004581:Electronics; D008027:Light; D008958:Models, Molecular; D010649:Phenylalanine / Q000737:chemistry*; D011789:Quantum Theory; D014443:Tyrosine / Q000737:chemistry*
chemical_list: D014443:Tyrosine; D010649:Phenylalanine