SEMI-EMPIRICAL METHOD FOR DETERMINING THE CROSS-SECTIONS FOR THE LOSS OF ELECTRONS BY FAST MULTIPLY CHARGED IONS

This paper describes a semiempirical method for calculang the cross sections σi,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 σi,i+m for various ions one can find the cross sections for the loss of an individual electron σnl which are practically independent of the number of electrons qnl in a shell nl. This makes it possible to calculate the cross sections σnl and the cross sections for the increase in charge, Si = Σmσi,i+m, for any other ion. The values of the cross sections σi,i+m are then extracted from those of Si in accordance with the relative probability Pm 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 σi,i+m (m = 1-5) have been calculated for fast ions of iodine and uranium in nitrogen. © 1979.