Vanadium L(Ii, III) X-Ray Emission and Absorption Spectra from Metal, Oxides, Nitride, Carbide and Boride

摘要

The vanadium L(II, III) X-ray emission and absorption spectra (wavelength about 24A) from pure metal, oxides, nitride, carbide, and boride were investigated using a plane-crystal vacuum spectrometer with electron beam excitation and flow-proportional detection. Emission spectra were studied over a wide range of accelerating voltages and takeoff angles, showing that satellite emission and self-absorption effects can cause gross distortion in band shapes. A replica of the L(II, III) absorption spectrum can be constructed solely from emission spectra afflicted with widely different amounts of self-absorption. The L(II, III) emission spectra from the oxides and nitride exhibit an anomalous crossover transition from the 2p level of the anion to the L(II) and L(III) levels of vanadium. This transition appears to be related to the degree of anion-cation orbital overlap and to the electrical properties of the material. Energy shifts of emission bands and absorption edges indicate the charge flow from vanadium to anion in the oxides and nitride. The L(III) edges are used to estimate the width of the forbidden gap in V2O5. Oxygen K emission from the oxides exhibits a peculiar dependence on the dispersing crystal used and is also influenced by satellite emission and self-absorption. (Author)