Theory of atomic photoionization measurements

Abstract

The theory of photoionization measurements for a general atomic system is developed in terms of a density matrix which determines the ejected electron and residual ion polarizations as a function of the target atom and incident photon polarization states. Expressions are derived which relate the photoelectron angular distribution and spin polarization parameters to the reduced matrix elements for the photoelectric transition. These expressions incorporate the fine structure of the atomic levels and the complete interaction between the residual ion and the ejected electron. The polarization of the residual ions which are formed in excited states is treated in terms of the subsequently emitted decay radiation.