Single- and Double-Quantum Photodetachment of Negative Ions

Abstract

The recent measurement of the transition probability for the double-quantum detachment of an electron from ${\mathrm{I}}^{\ensuremath{-}}$ has prompted a new theoretical study of this problem. A central-field model for bound and free states is used, in which a parameter is adjusted in the potential to yield the observed binding energies of the negative ions. An implicit-sum method, requiring the solution of inhomogeneous radial equations, is used to evaluate the sums over intermediate states. The results for ${\mathrm{I}}^{\ensuremath{-}}$ lie almost within the experimental uncertainty. The cross sections for single-quantum photodetachment and electron elastic scattering (from the neutral atom) are also given for the ions studied: ${\mathrm{C}}^{\ensuremath{-}}$, ${\mathrm{O}}^{\ensuremath{-}}$, ${\mathrm{F}}^{\ensuremath{-}}$, ${\mathrm{Si}}^{\ensuremath{-}}$, ${\mathrm{S}}^{\ensuremath{-}}$, ${\mathrm{Cl}}^{\ensuremath{-}}$, ${\mathrm{Br}}^{\ensuremath{-}}$, ${\mathrm{I}}^{\ensuremath{-}}$.