Spectroscopic Studies of Open-Shell Organic Cations in the Gas Phase

Abstract

The spectroscopic investigations of the radiative decay of openshell organic cations in the gas phase are reviewed. The studies carried out were focused on the detection of emission spectra, which were discovered for around hundred such cations. The emission spectra enabled the vibrational frequencies of several of the totally symmetric fundamentals of these cations in their ground states to be inferred and the lifetimes in the excited electronic state to be directly measured. Detailed studies of the relaxation channels and of the rate constants were based on the determined lifetimes, as well as on ancillary data forthcoming from other techniques, such as when fragmentation pathways are also accessible. The knowledge thus acquired on the relaxation behaviour of electronically excited open-shell cations under isolated conditions is discussed.