Line structure in photoelectron and Auger electron spectra of CuO_x/Cu and Cu by Auger photoelectron coincidence spectroscopy (APECS)

Abstract

In this study, we present Cu L3M45M45 Auger spectra in coincidence with Cu 2p3/2 from the oxidized surface of Cu (i.e. CuOx/Cu) and Cu 2p3/2 lines in coincidence with Auger 1G and 3F terms of Cu L3VV from Cu. Comparison of the L3VV line structures of CuOx/Cu with that of Cu reveals that the Auger line has changed to band‐like in the CuOx/Cu material. The reduced mean free path of the Auger electron in coincidence with the photoelectron displays the Auger line of the CuOx surface. The asymmetric broadening of the Cu 2p3/2 lines in coincidence with 1G and 3F terms from Cu illustrates that a single‐step model is essential for describing the Auger lineshape of copper. Copyright © 2001 John Wiley & Sons, Ltd.

Auger photoelectron coincidence spectroscopy: simplifying complexity

“…Despite using a slightly smaller pass energy (125 eV), a higher density of points and shorter acquisition time (about 90 h), the present data has considerably better counting statistics than that of the previous measurement. 41,50 The energy position of the 2p 3/2 photoelectron spectrum of Cu metal in coincidence with the L 3 -M 4,5 M 4,5 1 G Auger line in the present work coincides with that of the singles (XPS) line. This is consistent with the previous experiment.…”

“…28,30,51,53,54 We have previously reported the 2p 3/2 photoelectron spectrum of Cu metal measured in coincidence with the 1 G and 3 F terms of the L 3 -M 4,5 M 4,5 Auger line. 41,50 In coincidence with the 3 F term, the 2p 3/2 photoelectron was shifted to lower kinetic energy. In coincidence with the 1 G term it was narrowed on the low kinetic-energy side, but the centroid of the photoelectron line was unshifted from the position of the singles (XPS) line.…”

“…Recently, narrowing and lineshifts in the Cu 2p 3/2 photoelectron spectrum were observed, 41,50 which are properly understood only by recognising that the coincidence photoelectron spectrum is essentially different from the singles photoelectron spectrum; 51,52 the coincidence photoelectron spectrum is essentially the product of the initial core-hole spectral function divided by the energy-dependent imaginary part of the initial corehole self-energy, and the density of final states, whereas the singles photoelectron spectrum is essentially the initial core-hole spectral function. 51,53 When the imaginary part of the self-energy, the density of final states, or both, depend critically on the hole energy, the coincidence spectrum may depart significantly from the singles spectrum.…”

“…The original design of the spectrometer has been described elsewhere. 14,41 The most significant modification of the spectrometer is the implementation of parallel electron detection, which is described in the following section. Other modifications include installation of a fast-entry lock for introducing the sample into the UHV analysis chamber.…”

The Ag M5N45N45 Auger photoelectron coincidence spectra of disordered Ag0.5Pd0.5 alloy

“…The APECS apparatus used to make these measurements has been described previously [15]. A detailed description of the method used to obtain the coincidence data and conventional single spectra from random coincidence background in APECS is given by Thurgate [16].…”