Figure 7
Schematic illustration of SHI-induced excitation and fragmentation of oligopeptides via coupling between the electronic and vibrational excitation. The impinging SHI leads to excitation of the electronic subsystem only (sub-femtosecond timescale). The electronic excitation is converted into highly vibrationally excited molecules on the picosecond timescale. As a consequence, the covalent bonds most prone to the underlying fragmentation mechanism, i.e., in this case, the peptide bonds of the molecules’ backbone, are cleaved leading to the specific fragments observed in the mass spectra.
