Fully relativistic calculations of and fits to 1sionization cross sections

Abstract

The range of conditions for which inclusion of the generalized Breit interaction is important in calculating the scattering matrix elements for 1s ionization is explored within the relativistic distorted-wave approximation. This approach is applied to the calculation of 1s ionization cross sections for a variety of ions with one to four bound electrons and nuclear charge Z in the range of 10рZр92. These data are then interpolated with simple, but accurate, fit formulas. The resulting expressions are readily integrated over a relativistic Maxwellian electron distribution function to obtain rate coefficients for plasma modeling. A discussion of the high energy behavior of the cross sections for large Z is also given.

Electron impact ionization of hydrogen-like molybdenum ions

“…The formula of Aichele et al [3] has a similar tendency to that obtained by Fontes et al [10] until the cross section takes the maximum at 65 keV and then decreases gradually in contrast to that of Fontes et al [10]. In the formula of Fontes et al [10] the new term C was added to the fitting function which had been used for the fitting to obtain scaling formulae for the non-relativistic EI cross sections [6].…”

“…The variation of the cross sections with respect to the electron energy seems [2]. The curves are calculated with the scaling formulae proposed by Lotz [5] (dotted curve), Aichele et al [3] (dashed curve) and Fontes et al [10] (solid curve).…”

“…Fontes et al [10] performed theoretical calculation using the relativistic distorted wave method with the generalized Breit interaction included. They obtained a scaling formula by fitting a function to the result.…”

“…On the other hand, scaling formulae have been obtained by fitting appropriate functions to theoretical results. Recently, Fontes et al [10] obtained a scaling formula with the relativistic effects and the effect of Breit interaction considered, by fitting a function to their calculations. In the case of high-Z elements and high electron energies it is known that the relativistic effects and the effect of Breit interaction become more important [12].…”

“…Many scaling formulae for EI cross sections have been proposed due to the importance of the process for plasma modelling [1,3,[5][6][7][8][9][10]. The semi-empirical formula proposed by Lotz [5] is well known and has been used frequently.…”