Postcollision interaction effects inKLLAuger spectra following argon1sphotoionization

Abstract

Postcollision interaction effects on the Auger decay of a deep core hole are studied both experimentally and theoretically. KL 2,3 L 2,3 decay spectra of the Ar 1s vacancy are measured with high-energy resolution with excess photon energies ranging from 0 to 200 eV above the ionization threshold. Interaction of the Auger electron with the photoelectron and the ion field manifests itself in the Auger spectra as a distortion of the energy distribution of the Auger electron close to threshold. Moreover, recapture of the photoelectron due to energy exchange is dominating in the low-photon-energy range above threshold. The experimental results are compared with calculations based on the semiclassical approach to the postcollision interaction. The energies of the discrete levels and individual recapture cross sections are computed in the Hartree-Fock approximation. Good agreement is found between the calculated and experimental spectra, validating the model used.

Interplay of complex decay processes after argon 1s ionization

“…Measurements were performed at a photon energy 6 eV above the 1s ionization threshold (3206.26 eV [15]), and on top of the 1s → 4p transition at 3203.5 eV, and 1s → 5p transition at 3205.1 eV. The photon energy above threshold was chosen to minimize the effects of post-collision interaction and electron recapture on the ion rates [17,30], while photoelectrons are still slow enough so they can be efficiently measured within a 4π solid angle using a low extraction field.…”

“…In this study, the electron spectrometer resolution was estimated to be ∼180 meV at 100-eV pass energy and the photon bandwidth delivered by the beamline is 350 meV at 3200-eV photon energy. Auger decay spectra were recorded on top of the 1s → 4p and 1s → 5p transitions, and 20 eV above the ionization threshold, high enough to minimize the effect of post-collision interaction on the Auger lines [30], and low enough to neglect recoil effect such as measured on neon at high photon energy [32].…”

Hard x-ray photoelectron spectroscopy on heavy atoms and heavy-element containing molecules using synchrotron radiation up to 35 keV at SPring-8 undulator beamlines

“…the resolving power E/ΔE higher than 5000 (where E is the kinetic energy of electron and ΔE the instrumental resolution), are quite scarce. Up to now, the GALAXIES beamline at the SOLEIL synchrotron [2,3] has been the only facility for high-resolution HAXPES experiments on atomic and molecular science and has been achieving significant results on double-core-hole spectroscopy [4][5][6][7], recoil effects [8][9][10], ultrafast phenomena [11][12][13], post-collision interaction (PCI) [14,15], resonant Auger processes [16][17][18][19][20], and very recent studies on aqueous solution [21,22]. The experiments at the GALAXIES beamline, however, are limited to the excitation energy ranging between 2.3 and 12 keV, while experiments with much higher photon energy are quite scarce.…”

Detailed assignment of normal and resonant Auger spectra of Xe near the L edges

“…Their contributions in the present spectra are indicated by vertical arrows labeled with RA and caused by a recapture of the continuum photoelectron to a discrete state during the Auger decay [11]. In principle such resonant Auger contributions should be visible in all Auger transitions measured subsequent to photoionization directly above the corresponding L threshold.…”

“…In addition, ultrafast nuclear motion on the femtosecond and even subfemtosecond time scale [8] as well as ultrafast dissociation following core excitation and subsequent Auger cascade [9,10] can be observed. Because of the very short lifetimes of the deep core-hole states such as Ar 1s − 1 and high kinetic energies of Auger electrons, large postcollision interaction (PCI) effects are also reported [11]. Finally, alternative effects such as electronic state-lifetime interference can be found [12][13][14][15].…”