H. Aksela

The resonant Auger effect

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.

The vibrationally resolved participator Auger spectra of selectively excited C 1s(2σ)−12π1 vibrational states in carbon monoxide

The fully vibrationally resolved participator Auger spectra originating from the decay of the C 1s(2σ)−12π1 resonance in CO are presented. The C 1s(2σ)−12π1 v’=0 resonance has been excited with a 75 meV monochromator bandpass, i.e., in Auger resonant Raman conditions, and the participator Auger spectrum observed. The C 1s(2σ)−12π1 v’=1 resonance is also excited and the corresponding participator Auger spectrum observed with a monochromator bandpass slightly larger than the inherent width. The results are compared to theoretical simulations using coherent lifetime‐vibrational interference theory which accounts for the details of the spectrum. We have observed an interference shift on the transitions to different vibrational sublevels in the final state. A high resolution C 1s photoelectron spectrum of CO is also presented. The lifetime width of the C 1s core–hole state is determined to be 97(10) meV, whereas the C 1s(2σ)−12π1 resonance is measured to have a width of 86(10) meV.

Auger decay of the dissociating core‐excited states in the HCl and DCl molecules

High‐resolution Auger electron spectra from the decay of the Cl 2p→σ* excitation in HCl and DCl have been measured. The spectra are analyzed, separating molecular and atomic features, which are assigned to transitions to the HCl (5σ2π)4σ* and Cl (3s3p)6 states, respectively. Auger line shapes, as affected by the molecular dissociation, are studied by comparing the experiment with the results of Monte‐Carlo computer simulations based on a semiclassical model.

Correlation effects in the - MM Auger transitions of Ar

- MM Auger spectra of argon have been measured with very high resolution using excitation by monochromatic synchrotron radiation. The photon energy was selected slightly above the 2p ionization threshold for creation of the single 2p core hole state only. The Auger spectra are thus free from any satellite lines originating from two-hole initial states and therefore well suited to study the configuration interaction in the final ionic state of the decay. Electron correlation is investigated by calculating the energies and intensities of the transitions using the multiconfiguration Dirac - Fock method and by comparing them with the experimental results.

Solid State Effects in the Auger Electron Spectra of Magnesium, Zinc and Cadmium

High resolution KLL Auger electron spectrum from magnesium, L2,3M4,5M4,5 spectrum from zinc, and M4,5N4,5N4,5 spectrum from cadmium have been measured for both vapour and solid phases using electron impact excitation. In order to observe in detail solid state effects in these Auger spectra and to minimize the contribution of instrumental differences, the measurements for the two phases were carried out with the same spectrometer. From decomposition of the line groups into individual lines was obtained line broadening on going from vapour to solid, (0.20 ? 0.10) eV for magnesium, (0.45 ? 0.10) eV for zinc and (0.47 ? 0.10) eV for cadmium. The kinetic energy shifts of the line components between vapour and solid were found to be (16.0 ? 0.5) eV, (13.7 ? 0.5) eV, and (12.2 ? 0.5) eV for magnesium, zinc, and cadmium, respectively. The calculated vapour-metal Auger energy shifts using Shirleys extra-atomic relaxation model are in agreement with our experimental results.

The Normal Incidence Monochromator Beamline I3 on MAX III

On the 700 MeV MAX III ring at MAX‐lab, a 6.65 m off‐axis eagle type monochromator beamline has recently been commissioned. The beamline is sourced by an apple type variable polarization undulator. The energy range of the beamline is 4.6–50 eV and the resolving power achieved is more than 100,000. There are two branch lines, one for angle and spin resolved photoemission studies from solids and the other for gas phase and luminescence experiments. We present the design and performance of the beamline.

FAST DISSOCIATION OF RESONANTLY CORE EXCITED H2S STUDIED BY VIBRATIONAL AND TEMPORAL ANALYSIS OF THE AUGER SPECTRA

Excitation of a core electron to the lowest unoccupied orbital of H2S has been shown to give rise to dissociation that occurs faster than the Auger decay. Recent experimental data have allowed us to resolve vibrational structures connected with the resona

Decay of the , and states of Ar studied by utilizing the Auger resonant Raman effect

The 2p electrons of Ar have been excited selectively to the 4s, 3d and 4d orbitals and high-resolution de-excitation spectra have been recorded by utilizing the Auger resonant Raman effect. Fine structures in the resonant Auger spectra have been clearly resolved for the first time. The roles of shake transitions and configuration interaction between the and , n = 3 - 6 final states in producing the complicated fine structures have been discussed.

Solid state effects in the M4,5N4,5N4,5 Auger electron spectrum of cadmium

Abstract High resolution M 4,5 N 4,5 N 4,5 Auger electron spectra have been measured from cadmium vapour and from solid cadmium by using electron impact excitation. In order to observe solid state effects in the Auger spectrum in detail and to minimize the contribution of instrumental differences the measurements on the two phases were made with the same spectrometer. Decomposition of the line groups into individual lines gave the natural line widths (FWHM) 0.32 ± 0.05 and 0.79 ± 0.08 eV for free cadmium atoms and for solid cadmium, respectively. The energy shift of the line components on going from vapour to solid was found to be 12.2 ± 0.5 eV. The vapour—metal Auger energy shift has been calculated for an extra-atomic relaxation model. The calculated result agrees well with the observations. The solid state broadening of the lines seems to be related to the width of the range of the final state energies in the metal.

Semiempirical Solid State Shifts in the Auger-and Photoelectron Energies

Kinetic energy shifts of the Auger and photoelectrons between free atoms and their solid samples are studied for three series of consecutive elements: Na to Si, Cu to Se and Pd to Ba. The free atom binding and Auger energies are evaluated semiempirically for the elements for which experimental atomic data are not available. The obtained energies are also compared to the corresponding values from other calculation methods. With the aid of calculated atomic Auger energies and measured molecular Auger spectra also the molecular Auger shifts are obtained for several molecules. Experimental values for solid state shifts are obtained either from direct simultaneous vapour-solid measurements or from comparison between calculated or measured atomic energies and separate solid state measurements. The solid state Auger shifts are also calculated by applying the thermochemical model to the Auger process. Good agreement between calculated and experimental shift values are found through the studied series.