Auger electron angular distributions following excitation or ionization from the Xe 3d and F 1s levels in xenon difluoride

• Published in: Physical chemistry chemical physics : PCCP 2022-01, Vol.24 (3), p.1367-1379
• Main Authors: Forbes, Ruaridh, Hockett, Paul, Powis, Ivan, Bozek, John D, Pratt, Stephen T, Holland, David M. P
• Format: Article
• Language: English
• Subjects: Anisotropy; Augers; Decay; Difluorides; Electrons; Excitation spectra; Fluorine; Ionization; Ions; Kinetic energy; Linear polarization; Parameters; Photoionization; Photons; Synchrotron radiation; Synchrotrons; Vacancies; Xenon
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d1cp04797c

Linearly polarized synchrotron radiation has been used to record polarization dependent, non-resonant Auger electron spectra of XeF 2 , encompassing the bands due to the xenon M 45 N 1 N 45 , M 45 N 23 N 45 , M 45 N 45 N 45 and M 45 N 45 V and fluorine KVV transitions. Resonantly excited Auger spectra have been measured at photon energies coinciding with the Xe 3d 5/2 → σ* and the overlapped Xe 3d 3/2 /F 1s → σ* excitations in XeF 2 . The non-resonant and resonantly excited spectra have enabled the Auger electron angular distributions, as characterized by the β A parameter, to be determined for the M 45 N 45 N 45 transitions. In the photon energy range over which the Auger electron angular distributions were measured, theoretical results indicate that transitions into the f continuum channel dominate the Xe 3d photoionization in XeF 2 . In this limit, the theoretical value of the atomic alignment parameter ( A 20 ) characterizing the core ionized state becomes constant. This theoretical value has been used to obtain the Auger electron intrinsic anisotropy parameters ( α 2 ) from the β A parameters extracted from our non-resonant Auger spectra. For a particular Auger transition, the electron kinetic energy measured in the resonantly excited spectrum is higher than that in the directly ionized spectrum, due to the screening provided by the electron promoted into the σ* orbital. The interpretation of the F KVV Auger band in XeF 2 has been discussed in relation to previously published one-site populations of the doubly charged ions (XeF 2 2+ ). The experimental results show that the ionization energies of the doubly charged states predominantly populated in the decay of a vacancy in the F 1s orbital in XeF 2 tend to be higher than those populated in the decay of a vacancy in the Xe 4d level in XeF 2 . Electron spectroscopy following Xe 3d and F 1s ionization in XeF 2 elucidates the influence of core electrons on molecular bonding.