Alkali-metal negative ions. I. Photodetachment of Li−, Na−, and K−

Abstract

Photodetachment cross sections of the negative ions of the three lightest alkali-metal atoms have been calculated using configuration-interaction wave functions for the initial state and close-coupling scattering wave functions for the final state. Pronounced structure obtained at the threshold for leaving the neutral atom in the first excited state is due to a combination of real resonance behavior and the threshold law for collisional excitation. The range of validity of this law is, however, found to be very narrow. The shape of the cross sections in this region is in excellent agreement with experimental measurements. Results are also presented for the angular distribution of the photoelectrons following photodetachment with simultaneous neutral excitation, for the dipole polarizabilities of the negative ions, and simple analytic formulas for the radiative attachment coefficients.