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Title: Time evolution of a two-hole state in Auger-induced desorption

Abstract

The dynamics of an Auger-induced desorption of an adatom from the crystal surface is investigated theoretically. A model is proposed which describes the competition between the fundamental interactions in the desorption processes, such as the destabilization of the adatom in the two-hole state, the hopping of the holes to the surface, and the Coulomb repulsion between the localized two holes. A full quantum mechanical formalism is presented to calculate the temporal evolution of the three-body system composed of two holes and one atom. The probability of desorption is calculated as a function of the parameter values of the fundamental interactions. It is shown that the on-site Coulomb repulsion plays an important role to stabilize the two-hole state against the neutralization and, therefore, to enhance the probability of desorption of the adatom.

Authors:
; ;  [1]
  1. Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)
Publication Date:
OSTI Identifier:
20719839
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 72; Journal Issue: 20; Other Information: DOI: 10.1103/PhysRevB.72.205335; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; ATOMS; AUGER EFFECT; COULOMB FIELD; CRYSTALS; DESORPTION; EVOLUTION; HOLE MOBILITY; HOLES; LAYERS; PROBABILITY; QUANTUM MECHANICS; SURFACES; THREE-BODY PROBLEM

Citation Formats

Yasui, Akira, Uozumi, Takayuki, and Kayanuma, Yosuke. Time evolution of a two-hole state in Auger-induced desorption. United States: N. p., 2005. Web. doi:10.1103/PhysRevB.72.205335.
Yasui, Akira, Uozumi, Takayuki, & Kayanuma, Yosuke. Time evolution of a two-hole state in Auger-induced desorption. United States. doi:10.1103/PhysRevB.72.205335.
Yasui, Akira, Uozumi, Takayuki, and Kayanuma, Yosuke. Tue . "Time evolution of a two-hole state in Auger-induced desorption". United States. doi:10.1103/PhysRevB.72.205335.
@article{osti_20719839,
title = {Time evolution of a two-hole state in Auger-induced desorption},
author = {Yasui, Akira and Uozumi, Takayuki and Kayanuma, Yosuke},
abstractNote = {The dynamics of an Auger-induced desorption of an adatom from the crystal surface is investigated theoretically. A model is proposed which describes the competition between the fundamental interactions in the desorption processes, such as the destabilization of the adatom in the two-hole state, the hopping of the holes to the surface, and the Coulomb repulsion between the localized two holes. A full quantum mechanical formalism is presented to calculate the temporal evolution of the three-body system composed of two holes and one atom. The probability of desorption is calculated as a function of the parameter values of the fundamental interactions. It is shown that the on-site Coulomb repulsion plays an important role to stabilize the two-hole state against the neutralization and, therefore, to enhance the probability of desorption of the adatom.},
doi = {10.1103/PhysRevB.72.205335},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 20,
volume = 72,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}
  • We present evidence for a fundamentally new mechanism for impact-induced desorption, viz., core-hole Auger decay. We thereby explain why observed thresholds for electron-stimulated desorption (ESD) of positive ions (O/sup +/, OH/sup +/, and F/sup +/) from certain d-band metal oxides (TiO/sub 2/, V/sub 2/O/sub 5/, and WO/sub 3/) correlate in energy with the ionization potential of the highest-lying atomic core levels. We conclude that electron-stimulated desorption is in many interesting cases an atom-specific, valence-sensitive probe of surfaces.
  • We report the first observation of a localized two-hole electronic excitation on a covalently bonded surface. We find that the electron-stimulated desorption threshold for this system corresponds to the localized state energy. This suggests that localized multihole excitations are important dissociation channels in extended covalent systems.
  • Positron-annihilation-induced Auger-electron spectroscopy (PAES) was used to study the effects of oxygen, residual gases, and temperature on a Ge(100) surface. Three low-energy Auger peaks were detected at 50, 90, and 100--150 eV, attributed to {ital M}{sub 2,3}{ital M4}{ital M4}, {ital M}{sub 2,3}{ital M4}{ital V}, and {ital M}{sub 1}{ital M4}{ital M4} Auger transitions, respectively. An estimated (4{plus minus}1)% of the surface-trapped positrons annihilate with Ge 3{ital p}--level electrons. The sensitivity of PAES to the surface condition is demonstrated. The PAES yield from a Ge(100) surface is reduced at elevated temperatures, in accord with an activation process earlier found in several positroniummore » (Ps) -fraction experiments. A desorption model adopted from these studies does not describe accurately the PAES results at higher temperatures ({gt}500 {degree}C), where the PAES intensity levels off to 5% of the room-temperature value. Possible sources for the discrepancy are discussed and models for positron trapping to deep surface traps are introduced. On the Ge(100) surface, an upper limit for Ps emission near the melting point is 97%. The error in calibration parameters due to the earlier assumption of 100% Ps emission seems to introduce only small errors into the Ps-fraction measurements.« less
  • No abstract prepared.