Free-atom behavior of Auger electrons in solids

X-ray emission and Auger electron emission are alternate modes of deexcitation of an atom with an inner-shell hole. If this atom is in a solid, and the electron which fills the inner-shell hole originates from the occupied valence band, the resulting x-ray emission spectrum will reflect the structure of the valence band. This is the basis for the well-established technique of band structure studies by means of soft x-ray spectroscopy. Analogously, if one or both electrons involved in the Auger process originate from the band, it can be expected that band structure information should also be reflected in the Auger spectra. Experimental evidence that this is not the case for the d-band metals such as Cu, Zn, Ag, and Cd is presented. It is shown that the Auger spectra resulting from transitions involving band electrons do not exhibit band structure, but rather show characteristics of free atoms. Explanations for this phenomenon as well as some interesting physical implications are discussed