A variety of characteristic behaviour of resonant KL₂₃L₂₃Auger decays following Si K-shell photoexcitation of SiCl₄

Abstract

Spectator resonant Auger electron spectra with the Si 1s photoexcitation of SiCl 4 have been measured using an electron spectroscopic technique combined with undulator radiation. The transition with the highest intensity in the total ion yield (TIY) spectrum, coming from excitation of a 1s electron into the 9t 2 valence orbital, generates the resonant Auger decay in which the excited electron remains in the 9t 2 orbital. A TIY peak positioned slightly above the 1s ionization threshold induces Auger decay in which the slow photoelectron is re-captured into a higher lying Rydberg orbital or the normal Auger peak shape is distorted due to a post-collision interaction effect. Another structure above the threshold, originating from a doubly excited state, yields the normal Auger peak with the distortion of peak shape and a resonant Auger peak with a higher kinetic energy. These findings provide a clear understanding of the properties of the excited orbitals which were ambiguous previously.

Molecular cascade Auger decays following Si KL23L23Auger transitions in SiCl4

“…In figure 1(d) the experimental TIY spectrum is displayed with a solid curve and the photoabsorption spectrum calculated using the density functional theory is illustrated with a broken one. The peak at 1846.2 eV is ascribed to excitation of a 1s electron into the 9t 2 orbital [26,35]. The peak at 1851.3 eV is associated with the excitation into high Rydberg orbitals.…”

“…At first it is appropriate to concisely indicate the resonant Si KL 23 L 23 Auger electron spectra of SiCl 4 reported in the literature [26]. Figure 1 shows resonant Auger electron spectra ((c) and (b)) at two photon energies (1846.2, and 1851.3 eV), together with the normal Auger electron spectrum (a) and the total ion yield (TIY) spectrum (d), derived from the previous paper [26]. This ion yield approximates the photoabsorption spectrum.…”

“…As shown in figure 1(c), the spectator resonant Auger electron at the photon energy of 1846.2 eV emerges dominantly at a kinetic energy of 1607.8 eV (V), and is assigned to the transition into the (Si 2p −2 ): 1 D 2 9t 2 state in an atomic representation of Si atom, and the one at 1601.0 eV with a lower yield (V shake-up) corresponds to 1 D 2 5p state. The electron spectrum at 1851.3 eV, figure 1(b), shows the highest peak at 1601.2 eV (NA), assigned to 1 D 2 of the normal Auger peak distorted due to the post-collision interaction [26,36]. A small broad structure around 1607.1 eV (Rec) is the result of a photoelectron-recapture followed by the Auger decay, and corresponds to the final state of 1 D 2 5p.…”

“…For a long time it was very difficult to produce an intense monochromatic photon beam in the energy region of excitation of Si 1s electrons. However, recent advances in the undulator beam line at SPring-8 and in highly sensitive electron spectrometers have enabled us to measure electron spectra at an appropriate resolution for electrons generated through photoexcitation of Si 1s electrons [23][24][25][26][27][28][29][30]. In resonant KLL Auger electron spectra of Si-containing molecules, Auger decays dominantly yield molecular ion states with a component of the 1 D 2 term of the Si atom, and the excited electron behaves as a spectator in these decays [23][24][25][26][27].…”

“…However, recent advances in the undulator beam line at SPring-8 and in highly sensitive electron spectrometers have enabled us to measure electron spectra at an appropriate resolution for electrons generated through photoexcitation of Si 1s electrons [23][24][25][26][27][28][29][30]. In resonant KLL Auger electron spectra of Si-containing molecules, Auger decays dominantly yield molecular ion states with a component of the 1 D 2 term of the Si atom, and the excited electron behaves as a spectator in these decays [23][24][25][26][27]. The final state of this process has two holes in the Si 2p subshell and subsequently emits other electrons, cascade Si LVV Auger electrons.…”