American Physical Society, Physical review B, 11(72)
DOI: 10.1103/physrevb.72.115407
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The structure and electronic properties of vanadium oxide nanotubes have been studied using optical, photoemission, and electron energy-loss spectroscopies. Electron diffraction indicates the tubular structure with an interlayer distance of about 26.1 angstrom. Photoemission spectroscopy gives an atomic ratio of vanadium to oxygen of 1:2.5, which is very close to vanadium pentoxide. From V 2p core-level photoemission and vanadium L-edge excitation spectroscopy, an averaged vanadium valency of about 4.4(+) is obtained. The lowest lying (interband) electronic excitations reflect this mixed valency. These excitations are rather localized as revealed by essentially no dispersion as a function of momentum transfer in electron energy-loss spectroscopy.