Theoretical interpretation of Penning and associative ionisation in collisions between two excited rubidium atoms

Abstract

Associative and Penning ionisation cross sections, rho AI and rho PI are calculated for collisions of two excited atoms Rb(nl)+Rb(5p 2P32/) in the classical impact parameter formulation for nl=5d to 9d and 7s. It is shown that the very large Penning ionisation rate constants, measured by the authors and presented earlier, can be well explained by such a model in terms of direct and exchange autoionisation widths, as well as the associative ionisation contributions which have been observed to be quite different for ns and nd cases.