Relative intensity changes ofL3MMAuger transitions in maximal-valent V and Cr compounds under ion bombardment

We have studied the $L_3\mathrm{MM}$ Auger spectra of V and Cr compounds where V and Cr exist in their maximal-valent state, with a nominally $3d^0$ electronic configuration. Using argon-ion bombardment as a means of in situ reduction of the valence state of V and Cr in these compounds and hence increasing the $3d$ character in the valence band, we show that this change causes a pronounced enhancement of the $L_3{M}_{23}{M}_{45}$ and $L_3{M}_{45}{M}_{45}$ transitions relative to the $L_3{M}_{23}{M}_{23}$ transition. Thus the relative intensities of these Auger transitions may be used as a sensitive indicator of the $3d$ character in the valence band. Such enhancement may also be viewed as a relative shift of the $L_3{M}_{23}{M}_{45}$ and $L_3{M}_{45}{M}_{45}$ transitions from what may be thought of as an interatomic to an intra-atomic character.