Fluorescence detection is a convenient way to measure x-ray absorption spectra in situations where samples cannot be made in the required configuration. However, self-absorption effects cause considerable distortion of spectra measured in fluorescence. We describe a straightforward procedure to correct for such distortion in the hard-x-ray region using the known energy dependence of the x-ray absorption coefficients. This procedure is used to obtain the vanadium K-edge spectrum of single crystal V 2 O 3 and we demonstrate that self-absorption is properly corrected. This facilitates the use of fluorescence detection even in the hard-x-ray region.

V 2 O 3 exhibits as a function of temperature a metal-insulator transition ͑MIT͒ associated with a structural and a magnetic transition, which we have studied with x-ray-absorption measurements of V 2 O 3 at the V 2p and O 1s edge as well as photoemission measurements above and below the MIT. The O 1s edge shifts ϳ0.3 eV to lower energy in the metallic phase and the linear dichroism is enhanced in the insulating state, an enhancement discussed in a molecular-orbital picture. These effects are independent of whether the insulating state is achieved by cooling, Cr doping, or stress. We conclude the monoclinic distortion plays only a minor role in the MIT; the major factor is the change in the c/a ratio. The V 2 p edge is much narrower in the insulating phase, perhaps due to changes in electron phonon coupling.

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the projected unoccupied O 2p and V 3d DOS respectively, indicating that atomic and solid state effects, including V-O hybridization, must be included to adequately describe the spectra.

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