High-resolution photoemission in low-dimensional conductors and superconductors

We report some of the results of extensive experimental and theoretical studies by our group of the high energy Auger spectra of the 4d metals and some of their alloys. We consider, separately, three aspects of these spectra: comparison of experiment with atomic theoretical calculations; the relationship between the Auger kinetic energies and the screening mechanisms in these metals; and the unique properties of satellites associated with these spectra, especially with the L1,2,3M4,5M4,5 spectra. Comparison with atomic theory yields some discrepancies that should be taken into account in the formulation of the theories. Consideration of the Auger kinetic energies yields insight into screening mechanisms and suggests methods for extracting electronic structure changes in alloys from XPS and XAES shifts. Systematic studies of the satellites permit their identification as arising from shake-up processes without contributions from of Coster-Kronig processes, in contrast to studies of 3d metals, such as Cu. Synchrotron studies allow the observation of the transition from the adiabatic approximation regime to that of the sudden approximation.