Elastic Scattering from Atomic Oxygen and Photodetachment fromO−

A method developed by Temkin to allow for polarization effects in low-energy scattering of electrons from atoms has been extended to include all direct contributions from the polarized orbitals and the exchange contribution from the most important type of polarized orbital. The analysis has been applied to atoms with configurations $1s^{2}2s^{2}2p^q$. Cross sections for the elastic scattering of slow electrons by atomic oxygen are given for energies <6.5 eV. The additional direct polarization terms are found to be important in calculating $s$-wave elastic cross sections for O, as they decrease the cross section by a factor of 2 near threshold; but the exchange $d$ orbitals of the oxygen atom are relatively unimportant in relation to all direct polarization terms. Photodetachment cross sections for ${\mathrm{O}}^{-}$ are given for photon energies in the range 1.47 to 5.5 eV, and are found to be in good agreement with experiment when polarization terms are included and the dipole velocity approximation is used.