New correlation effects in the photoionization of atoms and ions

Recent advances in experimental and computational capabilities have provided the impetus for highly detailed studies of the photoionization process in atoms and ions. As a result, there have been a number of new phenomena uncovered. And these new phenomena are, in a general sense, of correlation among the atomic electrons, i.e., the breakdown of the single-particle approximation. Of particular interest are cases where correlation is not merely a small perturbation on the single-particle model, but where correlation dominates the process. In this paper, a number of illustrative experimental and theoretical examples are presented in which electron-electron correlation is seen to be a primary determinant of the process.