Doubly differential cross section for electron detachment fromH−in high-velocity collisions with He

Abstract

In the context of the plane-wave Born approximation, three models of ascending complexity are used to calculate the doubly differential cross section for the process ${\mathrm{H}}^{-}+\mathrm{He}\to \mathrm{H}\mathrm{}\left(1s\right)+e+{\mathrm{He}}^{\mathrm{}(*)\mathrm{}}$. The first model uses a one-electron orthogonalized-planewave description of the $e$+H system. The second model uses a local potential to describe the interaction of the $e$+H system as a function of separation and includes $s$ and $p$ waves of the continuum. The third model uses a hyperspherical description of the two electrons which is fully antisymmetrized, and includes dynamic radial correlation, but is restricted to the lowest adiabatic channel. Each model is successively more appropriate to describe the low-energy continuum of the $e$+H system. In each model the doubly inelastic channel (He target excited) is the dominant process in the region of the large doubly differential cross section. The double-peaked structure observed experimentally is mainly due to electron correlation effects. The doubly differential cross section for electron detachment from ${\mathrm{H}}^{-}$ appears to be an excellent proving ground for theoretical models of the H+$e$ system at low levels of excitation. It is sensitive to many details of the description of the system: lowenergy phase shifts and radial and angular correlation.