The contribution to electron detachment in low-energy ${\mathrm{H}}^{\mathrm{-}}$(${\mathrm{D}}^{\mathrm{-}}$)-Na collisions due to a direct transition from the bound ground state of (HNa${)}^{\mathrm{-}}$ to the (HNa+$e^{\mathrm{-}}$) continuum is studied in an effective-range approximation, based on ab initio calculations. Neutralization of ${\mathrm{H}}^{\mathrm{-}}$ in collisions with Na atoms is shown to be dominated by this direct detachment process at low collision energies. At higher collision energies, charge transfer to (H+${\mathrm{Na}}^{\mathrm{-}}$) and detachment via charge transfer (previously studied by R. E. Olson and B. J. Liu [J. Chem. Phys. 73, 2817 (1980)]) become the dominant ${\mathrm{H}}^{\mathrm{-}}$ neutralization mechanisms. These theoretical results are compared with the experimental data of Y. Wang, R. L. Champion, and L. D. Doverspike [Phys. Rev. A 35, 1503 (1987)]. A new calibration of these measurements is proposed, based on a comparison with previous absolute measurements at higher energies by A. M. Howald, L. W. Anderson, and C. C. Lin [Phys. Rev. A 24, 44 (1981)].

• Received 4 February 1988

DOI:https://doi.org/10.1103/PhysRevA.38.2284