EXCITATION ACCOMPANYING PHOTOIONIZATION IN ATOMS AND MOLECULES AND ITS RELATIONSHIP TO ELECTRON CORRELATION

Abstract

If electron correlation is neglected, the photoelectric effect requires that only one electron be ejected from an atom. Experimentally, however, it is found in the photoionization process that there is a high probability for simultaneous excitation or ionization of a second electron in the same atom. This extra excitation can be explained by electron correlation : in some cases implicitly through the use of single-electron wave functions as in electron shake-off calculations, and in other cases through the use of wave functions that explicitly include correlation. We have utilized two recently constructed high resolution electron spectrometers to measure satellite lines in the photoelectron spectra of both the inner and valence shells of the rare gases and some simple gaseous molecules. These satellite lines are interpreted in terms of transitions to excited states of the singly charged ion, and are used to form a broader basis for the understanding of simultaneous excitation as the result of the photoelectron process