Observation and characterization of the CH5 radical by neutralized ion beam techniques

The CH5(CD5) radical has been produced by charge transfer neutralization of fast ion beams using Na and Zn targets. The results obtained with Na targets are in excellent agreement with previous similar studies using alkali metal targets. In particular, no evidence for metastability was observed. Alternatively, results obtained with Zn targets show clear evidence for production of metastable states of the radical with lifetimes in the 1--10 μs range. Measurement of the kinetic energy released upon dissociation indicates that some neutral radicals produced in CH+5(CD+5)/Zn reactions have energies very close to the ionization limit. It is proposed that the observed metastability may be explained by the production of high Rydberg levels of the radical having sufficiently long radiative lifetimes