Auger-electron lineshapes in electron impact ionization: a calculation for non-coincidence experiments

Abstract The distortion effects of the post-collision interaction on argon L 2,3 M 2,3 M 2,3 Auger-electron lineshapes have been calculated for 300 eV, 500 eV and 2 keV electron impact inner-shell ionization. The calculations were based on the model of Kuchiev and Sheinerman (Kuchiev M Yu and Sheinerman S A 1987 Sov. Phys.-Tech. Phys. 32 879) applying our cross section data for secondary electrons, determined by a classical trajectory Monte Carlo method and in addition a continuum distorted wave method for 2 keV. The asymmetry parameters of the calculated peak shapes have been examined as a function of the projectile energy and the Auger emission angle and for some cases compared with our previous experimental results

Mid-IR and VUV spectroscopic characterisation of thermally processed and electron irradiated CO2 astrophysical ice analogues

The astrochemistry of CO2 ice analogues has been a topic of intensive investigation due to the prevalence of CO2 throughout the interstellar medium and the Solar System, as well as the possibility of it acting as a carbon feedstock for the synthesis of larger, more complex organic molecules. In order to accurately discern the physico-chemical processes in which CO2 plays a role, it is necessary to have laboratory-generated spectra to compare against observational data acquired by ground- and space-based telescopes. A key factor which is known to influence the appearance of such spectra is temperature, especially when the spectra are acquired in the infrared and ultraviolet. In this present study, we describe the results of a systematic investigation looking into: (i) the influence of thermal annealing on the mid-IR and VUV absorption spectra of pure, unirradiated CO2 astrophysical ice analogues prepared at various temperatures, and (ii) the influence of temperature on the chemical products of electron irradiation of similar ices. Our results indicate that both mid-IR and VUV spectra of pure CO2 ices are sensitive to the structural and chemical changes induced by thermal annealing. Furthermore, using mid-IR spectroscopy, we have successfully identified the production of radiolytic daughter molecules as a result of 1 keV electron irradiation and the influence of temperature over this chemistry. Such results are directly applicable to studies on the chemistry of interstellar ices, comets, and icy lunar objects and may also be useful as reference data for forthcoming observational missions