Scaling behavior of radiative recombination cross sections and rate coefficients

Abstract

Direct radiative recombination (RR) cross sections ${\mathrm{\ensuremath{\sigma}}}^{\mathrm{RR}}$ and rate coefficients ${\mathrm{\ensuremath{\alpha}}}^{\mathrm{RR}}$ are presented for all ions using the scaling property of the cross section in the parameter \ensuremath{\eta}=${\mathit{Z}}_{\mathrm{eff}}$/(${\mathit{ka}}_{0}$). The RR cross section is defined simply in terms of two parameters, \ensuremath{\eta} and the number of electrons N in the target ion. The RR rate coefficient ${\mathrm{\ensuremath{\alpha}}}^{\mathrm{RR}}$/${\mathit{Z}}_{\mathrm{eff}}$ in turn depends on two parameters, the scaled temperature (FTHETA=${\mathit{k}}_{\mathit{B}}$T/${\mathit{Z}}_{\mathrm{eff}}^{2}$) and N. An empirical formula for the effective charge ${\mathit{Z}}_{\mathrm{eff}}$ is constructed, which is weakly dependent on the electron energy ${\mathit{k}}^{2}$. The cross-section values can also be used in analyzing high-energy ion-atom collisions with radiative electron capture.