Binary-encounter form factor and its use in the calculation of inelastic cross sections involving Rydberg atoms

Abstract

The form factor is a key parameter to be evaluated in most theoretical approaches currently available for the calculation of inelastic collisional cross sections involving Rydberg atoms. The binary-encounter method is shown to offer a very powerful means for the rapid evaluation of this parameter. Analytical expressions of the form factor are derived from hydrogenic wave functions. Many comparisons between binary-encounter and quantal calculations establish the range of validity of the former method. It is shown that, in most situations of practical interest, this approach provides an easy and efficient way to compute the cross sections corresponding to inelastic collisions between Rydberg atoms and atomic or molecular targets.