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Statistical vs. non-statistical deactivation pathways in the UV photo-fragmentation of protonated tryptophan-leucine
G Grégoire1, H Kang, C Dedonder-Lardeux
1Laboratoire de Physique des Lasers du CNRS-Université Paris 13, Institut Galilée, 93430 Villetaneuse, France. gregoire@lpl.univ-paris13.fr
Abstract:
The excited state dynamics of protonated tryptophan-leucine ions WLH+, generated in an electrospray source, is investigated by photo-induced fragmentation in the gas phase, using femtosecond laser pulses. Two main features arise from the experiment. Firstly, the initially excited pipi* state decays very quickly with 2 time constants of 1 and 10 ps. Secondly, the transient signals recorded on different fragments are not the same which indicates two competing primary fragmentation processes. One involves a direct dissociation from the excited state that gives evidence for a non-statistical deactivation path. The other is attributed to a statistical decay following internal conversion to the ground electronic surface.
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