Unimolecular Decay of Polyatomic Ions Prepared by Multi‐Photon Ionization

Ladder switching in multi‐photon ionization is shown to have important consequences for the study of ion kinetics. In particular, it makes feasible the production of internal energy‐selected molecular ions in a two laser experiment. The metastable decay of these ions is monitored in a reflecting field time‐of‐flight mass spectrometer‐with a high mass resolution. In this way unimolecular decay constants of monoenergetic metastable parent ions have been measured as a function of internal energy. As a first example we have shown that C‐loss as well as H‐loss channels of C6H+6 are competing and originate from the same electronic state of the benzene cation.