Threshold Behavior of Inelastic-Scattering Cross Sections

Abstract

The behavior of scattering cross sections near an excitation threshold is examined for the case of long-range potentials. The theory is confirmed by computations of $e-\mathrm{L}\mathrm{i}$ scattering. Recent observations of threshold structure in $e-\mathrm{N}\mathrm{a}$ collisions are ascribed to a ${}_{}{}^1{}_{}{}^{}D$ resonance of ${\mathrm{Na}}^{-}$. A true cusp should occur only in the ${}_{}{}^1{}_{}{}^{}P$ partial cross section.