Theoretical study of ( e, 2e ) processes for valence orbitals of CH4 using a multicenter distorted-wave method

Abstract

A multicenter distorted-wave method is used to study the electron impact single ionization from the outer (${1t}_{2}$) and inner (${2a}_{1}$) valence orbitals of a ${\mathrm{CH}}_{4}$ molecule. The triple differential cross sections are calculated in coplanar asymmetric kinematics with the scattered electron energy at 500 eV and the ejected electron energy at 12, 37, and 74 eV, respectively. The nuclear term in the ionization transition amplitude is fully included, and the calculated results well reproduce the experimental measurements, especially for the ${2a}_{1}$ orbital, where excellent agreement has been achieved.