On a complete experiment on photoionization of atoms

Abstract

There are seven experimentally measurable parameters characterizing the photoionization of a closed shell atom in the electric dipole approximation, namely, the cross section, four parameters describing the photoelectron angular distribution and spin polarization, and two parameters describing the alignment and orientation of the residual ion. They are defined by five theoretical values, three dipole matrix elements and two phase shift differences. As a consequence, these seven experimental parameters are not mutually independent, and there must be two equations connecting them. One of these equations connecting the photoionization parameters was found earlier, and the second one for the particular case of photoionization of an np3/2 subshell of a closed shell atom is derived here. It connects the photoelectron parameters with the alignment and orientation of the residual ion. We also checked that there are no other independent relations between the parameters. From these facts it follows that a complete photoionization experiment is possible, and it must include the measurements of the parameters of both the photoelectron and the residual ion.