### Session P1: Posters and Coffee Break

3:30 PM–3:30 PM, Friday, October 6, 2006
UT Arlington, University Center Room: Rio Grande, 3:30pm-5:30pm

Chair: Robert Ramsey, Pete Williams, Marcus Hawkins, Heather Brown, University of Texas at Arlington

Abstract ID: BAPS.2006.TSF.P1.9

### Abstract: P1.00009 : Observation of the high sensitivity of Positron Annihilation induced Auger electron spectroscopy to thermally induced changes in the oxidation state of Cu atoms at the surface of previously oxidized Cu(100)

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Changes in the surface of an oxidized Cu(100) single crystal resulting from vacuum annealing over a temperature range from 20 $^{\circ}$C to 800 $^{\circ}$C has been investigated using Positron annihilation induced Auger electron spectroscopy (PAES). The PAES measurements show a large monotonic increase in the intensity of the annihilation induced Cu (M$_{2,3 }$VV) Auger peak as the sample is subjected to a series of isochronal anneals in vacuum up to annealing temperature 300 $^{\circ}$C. The intensity then decreases monotonically as the annealing temperature is increase to $\sim$600 $^{\circ}$C. The Ps fraction, f$_{PS}$ of these surfaces was found to have the opposite trend going from f$_{PS}$ = 0.79 for the surface before any annealing to f$_{PS}$ =0.51 after annealing at 300 $^{\circ}$C. These results provide a clear demonstration of the thermal reduction of the copper oxide surface after annealing at 300 $^{\circ}$C followed by re-oxidation of the copper surface at the higher annealing temperatures presumably due to the diffusion of subsurface oxygen to the surface.