Ionization Cross-Section of an Atom by De-Excitation of Another Metastable Atom through Collision

Abstract

A method for calculation of the ionization cross-section of an atom by de-excitation of another metastable atom through collision (Penning ionization cross-section) is proposed. The perturbed stationary state method is applied and Jeffreys’ approximation is used of the determination of the phase shift. Fano’s formula is applied to the coupling between the discrete state and the continuum and a parameter β is introduced by which the wave function is made to satisfy the initial condition. The method is applied to a long-range interaction V=−C_n⁄Rⁿ. The velocity dependence obtained is the same as that of the previous work. The cross-section in the case of n=3 is about half the value obtained by the impact parameter method.