Measurement of the full electron spectrum associated with the Ag N₃VV Auger transitions: Evidence for the contribution of multi-electron Auger processes

Journal Article · Fri Jun 21 00:00:00 EDT 2019 · Journal of Electron Spectroscopy and Related Phenomena

DOI:https://doi.org/10.1016/j.elspec.2019.06.006· OSTI ID:1569551

Joglekar, P. V. ^[1]; Gladen, R. W. ^[2]; Chirayath, V. A. ^[2]; Fairchild, A. J. ^[2]; Kalaskar, S. ^[2]; Shastry, K. ^[3]; Dong, Q. ^[4]; Hulbert, S. L. ^[4]; Bartynski, R. A. ^[5]; Werner, W. S. M. ^[6]; Weiss, A. H. ^[2]

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1. Univ. of Texas, Arlington, TX (United States); Symbiosis Skills and Open Univ., Village-Kiwale, Pune (India)
2. Univ. of Texas, Arlington, TX (United States)
3. Univ. of Texas, Arlington, TX (United States); R.V. College of Engineering, Bangalore (India)
4. Brookhaven National Lab. (BNL), Upton, NY (United States)
5. Rutgers Univ., Piscataway, NJ (United States)
6. Vienna Univ. of Technology, Vienna (Austria)

In this paper, we report the first measurement of the full energy spectrum (down to 0 eV) of electrons emitted from the surface of Ag(100) as a result of the N₃VV Auger transition. A comparison with a Monte-Carlo model was used to obtain an estimate of the contribution of multi-electron Auger processes to the low energy part of the Auger spectrum. The experimental Auger spectrum was obtained in time coincidence with photo-emitted 4p_3/2 core electrons from Ag using Auger-Photoelectron coincidence spectroscopy (APECS). The coincidence condition in APECS can remove most, but not all, spectral contributions from events unrelated to the Auger transition. The remaining contributions to the APECS spectrum from Auger-unrelated events, which are significant, were determined from a series of coincidence measurements of inelastically scattered valence band photoelectrons. The contribution from Auger-unrelated events was subtracted from the APECS Auger spectrum of Ag(100) to obtain the full Auger spectrum down to 0 eV. The resulting spectrum includes, in addition to Auger electrons emitted without energy loss, inelastically scattered Auger electrons. We observe that the spectral weight of the low energy tail (LET) in the APECS spectrum is reduced by more than a factor of two after subtracting the Auger-unrelated contributions. However, the intensity of the LET after this subtraction is still two times the integrated intensity in the Auger peak. A Monte Carlo model that includes the inelastic transport of the N₃VV Auger electrons through the surface showed that LET produced by the inelastic scattering of the Auger electrons has the same intensity as the integrated intensity in the Auger peak. The excess intensity in the experimental LET provides strong evidence that the Auger related spectrum also includes contribution from multiple electron emissions that are intrinsic to the creation and/or the Auger decay of the core hole. In conclusion, our estimate shows that as low as 20% to as high as 60% of the core hole decay events result in the emission of more than one Auger electron from Ag (100). This result demonstrates the need for a better understanding of the contribution of valence-electron correlations to the entire CVV Auger spectrum down to 0 eV.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0012704; AC02-98CH10886
• OSTI ID: 1569551
• Report Number(s): BNL-212170-2019-JAAM
• Journal Information: Journal of Electron Spectroscopy and Related Phenomena, Vol. 235, Issue C; ISSN 0368-2048
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
Electron spectroscopy
Coincidence spectroscopy
Auger electron
Photoelectron
Background elimination
Low energy tail (LET)