Oxidation processes of chromium dimer and trimer cations in an ion trap

Oxidation processes of chromium cluster cations, Cr 2 + and Cr 3 + , are investigated by kinetics measurements under multiple-collision conditions by using a temperature-controlled ion trap. Both of the reactants commonly generate Cr+ and CrO+ as final products. However, the major reaction pathway to CrO+ presents a sharp contrast; Cr 2 + produces it directly by a single O2 collision, whereas Cr 3 + does via an intermediate Cr2O+. Comparison of the kinetics of the intermediate with that of cold Cr2O+ generated in the cluster source reveals that the intermediate Cr2O+ is thermalized promptly with the buffer gas filling the trap.