Dissociation processes of Kr2+ and Kr3+ studied by threshold photoelectron-photoion coincidence measurements

A time-of-flight (TOF) ion mass spectrum in coincidence with threshold photoelectrons was measured in the photon energy region between the first and second dissociation limits of Kr2+ to examine the decay processes of the Kr2+ II(1∕2u) state. The measured TOF spectrum reveals that Kr+ fragment ions are produced through dissociation of the repulsive I(1∕2g) state, which can be formed by the decay process of the II(1∕2u) state accompanied with emission of photons. The potential-energy curve of the I(1∕2g) state is deduced with detailed analysis of the observed TOF spectrum, in which the radiative lifetime of the II(1∕2u) state was also derived to be 2.5μs. Additionally, evidence of the dissociation process of Kr3+ ions was obtained in the same photon energy region, where the dominant channel is Kr3+→Kr2++Kr.