The influence of the 4d bandwidth on the M4,5N4,5N4,5Auger spectra of Ag and MgAg

Abstract

High-resolution photoelectron spectroscopy measurements show that the 4d band is narrower in MgAg (2.0 eV) than in pure Ag (3.6 eV). These results are combined with measurements of the binding energy of the initial states and recent theoretical work to explain differences which have been observed between the M4,5N4,5N4,5 Auger spectra of Ag and MgAg. In MgAg all final-state components of the M4,5N4,5N4,5 transitions are too tightly bound to decay by delocalisation of the (4d2) states, the spectrum is quasiatomic and is in good agreement with atomic structure calculations. In the Ag Auger spectrum, only the 1S0, 1G4, 1D2 and 3P states have a quasiatomic character. The 3F4 and, to a lesser extent, the 3F2,3 components of the Ag spectrum are shown to be degenerate with delocalised (4d,4d) two-hole states and it is suggested that the rapid delocalisation of these components explains the apparent reduction in intensity of the M5N4,5N4,5:3F4 and M4N4,5N4,5:3F2,3 components of the Ag spectrum. A broad 'band-like' feature to the high-energy side of the M4,5N4,5N4,5 spectrum is reduced in the MgAg spectrum to 0.6+or-0.1 of its intensity in the Ag spectrum. This reduction is attributed to the narrower 4d band in MgAg.