Independent atomic information in the characterization of atomic photoionization

L. A. LaJohn and R. H. Pratt

Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260

Abstract:

Atomic photoionization at all energies can be characterized in terms of nuclear Coulomb properties (nuclear Coulombic matrix elements), plus low multipole (not beyond octupole) atomic screening contributions to the matrix elements, in obtaining predictions for differential cross sections accurate within an error limit of $1\%$. We indicate under what circumstances more than dipole screening contributions are needed to describe photoionization of neutral atoms. Quadrupole screening can be important except in the lightest elements. Octupole screening can be important in inner shells of intermediate Z atoms and in all shells of high-Z atoms.