A semiempirical method for determining the cross sections for the loss of electrons by fast multiply charged ions

Abstract

This paper describes a semiempirical method for calculang the cross sections σ i, i+ m for the loss of one and several electrons by fast multielectron ions, which is based on the results of an analysis of experimental data and theoretical calculations. In the proposed method, from the known values of σ i, i+ m for various ions one can find the cross sections for the loss of an individual electron σ nl which are practically independent of the number of electrons q nl in a shell nl. This makes it possible to calculate the cross sections σ nl and the cross sections for the increase in charge, S i = Σmσ i, i+ m , for any other ion. The values of the cross sections σ i, i+ m are then extracted from those of S i in accordance with the relative probability P m for the loss of m electrons. It is suggested that in the region of extremely high ion velocities the cascade filling of inner-shell vacancies is the predominant mechanism for the removal from a multielectron ion of several electrons. Using this method the cross sections σ i, i+ m ( m = 1–5) have been calculated for fast ions of iodine and uranium in nitrogen.