IONIZATION CROSS-SECTIONS FOR RYDBERG-ATOM-RYDBERG-ATOM COLLISIONS

A classical-trajectory Monte Carlo method has been applied to collisions of two Rydberg atoms. Numerical calculations were made for velocities v=0.01ve to 10ve, where the Rydberg electron's velocity ve(a.u.)=1n and n is the principal quantum number of the Rydberg atom. The total ionization cross sections scale as n4 and show a v-0.65 dependence at low v, a slight maximum around ve, and a rapid decrease at high v. The cross sections are almost an order of magnitude larger than n4a02 at thermal energies. © 1979 The American Physical Society.