Line Profiles in the Far-uv Absorption Spectra of the Rare Gases

TLDR

Theoretical analysis of rare‑gas absorption line profiles uses linewidth, q index, and correlation coefficient to relate to energy and dipole matrix elements, whose signs are crucial because the profiles arise from interference effects. The study aims to demonstrate a method for treating experimental data and to survey the information on dynamics of highly and multiply excited atoms made available by recent experimental techniques. The authors analyze line profiles by extending existing theory and estimate matrix elements from experimental evidence and atomic theory, then compare these estimates for consistency. The study tentatively explains similarities and differences among line profiles, discusses the link between Rydberg series and absorption edges, and accounts for downward jumps at certain edges.

Abstract

The line profiles of a dozen series of widely different appearance, observed recently in the rare-gas optical absorption spectra between 20 and 100 eV, are analyzed by adapting and extending previously developed theory. Theory characterizes each profile by its linewidth, $q$ index, and correlation coefficient $\ensuremath{\rho}$ and relates these parameters to matrix elements of the energy and of the electric dipole moment. Because the profiles result from interference effects, the signs of these matrix elements are highly relevant. Crude estimates of such, hitherto hardly accessible, matrix elements are obtained from experimental evidence and from atomic theory, and are intercompared and found to be in general agreement. Similarities and differences among the line profiles are thereby tentatively explained. The connection of Rydberg series and absorption edges is discussed and the occurrence of downward jumps at some edges is explained. This exploratory investigation demonstrates how one can treat experimental data, and it surveys the kind and volume of information on the dynamics of highly and multiply excited atoms made accessible by recent experimental techniques.