SPECTROSCOPY OF METALLIC AND INSULATING V2O3

V2O3 exhibits as a function of temperature a metal-insulator transitio n (MIT) associated with a structural and a magnetic transition, which we have studied with x-ray-absorption measurements of V2O3 at the V 2p and O Is edge as well as photoemission measurements above and below t he MTT. The O Is edge shifts similar to 0.3 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 2p edge is much narrower in the insulating phase, perhaps due to changes in electron phonon coupling.