A comprehensive review is given on photoionization of rare gas atoms using monochromatized synchrotron radiation. Emphasis is put upon the general experimental and theoretical background, and illustrative examples are presented in order to show the present status and the progress in the field during the last decade.

https://iopscience.iop.org/article/10.1088/0034-4885/55/9/003/pdf

Photoionization of atoms using synchrotron radiation

The latest, most important developments in (e,2e) studies are reviewed from an experimental point of view. These include ionization processes near threshold, the symmetric energy sharing collisions involving double scattering mechanisms, core states ionization, (e,2e) measurements for autoionizing states and for the simultaneous excitation and ionization of the target. Double ionizing processes with coincidence detection of two or three electrons in the final state are also reviewed, including (e,e'-Auger) experiments and the new born (e,(3-1)e) and (e,3e) domain.

https://iopscience.iop.org/article/10.1088/0953-4075/24/10/001/pdf

Recent developments and new trends in (e, 2e) and (e, 3e) studies

http://www.atomic-theory.uni-jena.de/pub/Ratip-cpc-2012b.pdf

The Ratip program for relativistic calculations of atomic transition, ionization and recombination properties ☆

A brief survey of the resonant Raman Auger effect is presented. An outline of experimental considerations and equipment is given. The theory of the resonant Auger effect is outlined within the context of a resonant photoionization process, which we hope will provide new researchers in the field a simplified feel for the physics involved. Our focus is on the atomic problem, but we include the connection to the molecular case with some accompanying discussion. Within this context we then discuss some examples which address a number of issues we feel are central to the subject: coherence between intermediate states, the treatment and meaning of correlation effects, the relation to the normal Auger effect, and the experimental complications due to incident-photon bandpass effects.

https://iopscience.iop.org/article/10.1088/0953-4075/33/2/201/pdf

The resonant Auger effect

This article reviews the current status of inner-shell spectroscopies of free atoms and molecules using high-resolution soft-x-ray monochromators installed in the soft-x-ray beamlines at the third-generation synchrotron radiation facilities. Beamlines and endstations devoted to atomic and molecular inner-shell spectroscopies and various types of experimental techniques, such as ion yield spectroscopy, resonant photoemission spectroscopy and multiple-coincidence momentum imaging, are described. Experimental results for K-shell excitation of Ne, O K-shell excitation of H2O and CO2, C K-shell excitation and ionization of CO2 and B K-shell excitation of BF3, obtained at beamline 27SU of SPring-8 in Japan, are discussed as examples of atomic and molecular inner-shell spectroscopies using the third-generation synchrotron radiation sources.

https://iopscience.iop.org/article/10.1088/0953-4075/36/4/201/pdf

High-resolution inner-shell spectroscopies of free atoms and molecules using soft-x-ray beamlines at the third-generation synchrotron radiation sources

The angular distribution and spin polarisation of Auger electrons following atomic collisions are discussed for the case where both the target atom and the projectile are unpolarised. General expressions for the angular distribution and polarisation of Auger electrons in the (LS)J coupling approximation are obtained and analysed. In the particular case of the p3/2 subshell vacancy the anisotropy coefficient and polarisation are expressed in terms of Auger-decay matrix elements. It is shown that spin-polarised Auger electron spectroscopy of atoms can provide new information on both the Auger process and the structure of atomic hole states, namely, the Auger-decay matrix elements and their relative phaseshifts.

https://iopscience.iop.org/article/10.1088/0022-3700/17/7/017/pdf

Angular distribution and spin polarisation of Auger electrons

A theoretical treatment is given of possible experiments on electron impact ionisation of inner atomic shells, in which an inelastically scattered electron is detected in coincidence with the decay products of the ion formed, namely with an X-ray photon or with an Auger electron. General expressions for the angular distribution and polarisation of the X-ray photons and Auger electrons are given in terms of the parameters describing the anisotropy of the ionic state, namely statistical tensors which depend on the electron scattering angle and are determined by the ionisation mechanism. The statistical tensors, the asymmetry and the polarisation of the X-rays and the asymmetry of the Auger electrons are calculated for ionisation of the 2p shell of Ar, the 3d shell of Kr and the 4d shell of Xe at different scattering angles of the fast electron.

The theory of coincidence experiments on electron impact ionisation of inner atomic shells

Experimental and theoretical study of the Auger cascade following 4d $\rightarrow$ 6p photoexcitation in Xe

It is shown that small energy-level splittings of resonance states in highly charged ions can be extracted from the angular correlations of characteristic x rays emitted in radiative cascades, which may ultimately be used for new tests of QED in highly charged ions.

Determination of small level splittings in highly charged ions via angle-resolved measurements of characteristic x rays

For pt.I see ibid., vol.13, p.1601 (1980). The alignment of ions with an inner-shell vacancy resulting from electron capture in ion-atom collisions is treated theoretically. The general expressions for the alignment are obtained in the Oppenheimer-Brinkman-Kramers and Born approximations. Simple analytical formulae for the alignment are derived within the framework of the hydrogenic model. The dependence of the degree of alignment on the incident particle velocity and the ratio of charges of the colliding particles is analysed. The alignment due to electron capture is shown to differ essentially from the alignment due to direct Coulomb ionisation. The sensitivity of the degree of alignment to the form of captured-electron wavefunctions and to the type of perturbing interaction is investigated. The experimental data on the angular distribution of Auger electrons in the ionisation of the 2p3/2subshell of Mg by protons and He+ ions are reanalysed taking into account the electron capture mechanism.

N M Kabachnik

Papers

Angular distribution and spin polarisation of Auger electrons

The theory of coincidence experiments on electron impact ionisation of inner atomic shells

Experimental and theoretical study of the Auger cascade following 4d $\rightarrow$ 6p photoexcitation in Xe

Determination of small level splittings in highly charged ions via angle-resolved measurements of characteristic x rays

Inner-shell alignment of atoms in ion-atom collisions. II. Electron capture