Photoelectron–photon-coincidence measurements of the fluorescence quantum yields of cis-1,2-difluoroethylene cation in selected levels of the Ã2A1 state

Abstract

Fluorescence quantum yields of the cis-1,2-difluoroethylene cation in the lowest vibrational levels of the òA₁ electronic state have been determined. The principle of the measurements is based on the detection of coincidences between energy-analysed photoelectrons and undispersed photons using He(Iα) as a photoionisation source. The cis-1,2-difluoroethylene cation in the òA₁ state is one of the few polyatomic cations for which the radiative decay as well as fragment ions are detected. The radiative, non-radiative and fragmentation rate constants could be evaluated from all the available data. These show that for the lowest levels of the òA₁ state the non-radiative pathway competing with the radiative relaxation is internal conversion (and/or isomerisation) as the fragmentation rate (loss of HF) is much slower.