Calculation of the singlet–triplet energy differences using the universal function

Abstract

A method to calculate the singlet–triplet energy differences in electron–atom (molecule) scattering is developed. The method uses the recently developed universal function, which can extrapolate the generalized oscillator strength through the nonphysical region to K2 (momentum transfer squared) = 0, to calculate the integral of the energy difference in the small K2 region. Cubic spline is used for the experimental data to evaluate the contribution to the integral numerically. The energy differences in the transitions 11S–21,3P in e–He and X1 Σ+–A1,3 Π in e–CO scattering are calculated and compared with measurements as illustrative examples.