Statistical versus non-statistical photo-fragmentation of protonated GWG tri-peptide induced by UV excitation

A new experimental method is described in which photo-induced fragmentation of protonated molecules in an electric field is investigated by the detection in coincidence of the ion and neutral fragments. This technique allows measuring fragmentation times, in the tens of nanosecond range, for each fragmentation channel independently. As an example, the method has been used to study the photo-fragmentation of the protonated tri-peptide GWG. It is shown that the various fragmentation channels have different fragmentation times. This is a clear signature of non-ergodic mechanisms occurring during fragmentation of such a large molecule. (C) 2007 Elsevier B.V. All rights reserved.