Inner shell alignment of atoms in photon impact ionization

Highlights: • Alignment parameter studied using different approaches. • Theory and empirical formulations compared with experimental measurements. • Explanation for interesting trends in variations of alignment parameter added in connection with electron filling patterns. - Abstract: The ionization of an atom can result in alignment of the residual ion. In the present work alignment studies are made for some of the high Z elements using different approaches. The theoretical values of the alignment parameter (A₂) have been calculated by using the non-relativistic dipole approximation in a point Coulomb potential and analytical perturbation theory in a screened Coulomb potential. Empirical alignment evaluations are done by interpolating experimental L x-ray fluorescence cross-sections along with radiative decay rates. The alignment results are further compared with available theoretical and experimental measurements.