Penning and associative ionisation of highly excited rubidium atoms

Abstract : Highly excited and resonant states are created in a rubidium vapour in order to study the collisional ionisation with the ground state and between these different excited species. A mass analysis allows us to separate the atomic and molecular channels. Penning ionisation with a resonant state is shown to have a great efficiency (rate coefficient greater than 10$^{-8}$ cm3 s$^{-1}$ for all the highly exited levels under study (6d, 8s, 7d). The associative ionisation rate coefficient between these excited atoms and a ground-state atom lies in the expected range, 10$^{-10}$ to 5 x 10$^{-10} $ cm$^3$ s$^{-1}$ and seems to be independent of $\it I$ and $\it j$ values.