Two-photon detachment of H−

Abstract

A precision calculation of the two-photon detachment cross section for ${\mathrm{H}}^{\ensuremath{-}}$ is performed by means of a non-Hermitian Floquet theory. A highly accurate initial state wave function is used along with fully correlated saddle-point wave functions for the intermediate and final states. The cross section is investigated for energies below the $n=2$ and $n=3$ thresholds. The peak cross section predicted for the ${}^{1}D$ resonance is $3.10\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}49}$ ${\mathrm{cm}}^{4}$ sec at 10.873 2 eV. It represents an ab initio theoretical prediction in complete agreement with the experimental result of 3.2 $(+1.8,\ensuremath{-}1.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}49}$ ${\mathrm{cm}}^{4}$ sec at 10.873 2(27) eV.