The surface structure of the metallic sodium tungsten bronze Na_0.667WO₃(001)

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• 作者：Jones ; F.H. ; Rawlings ; K. ; Dixon ; R.A. ; Fishlock ; T.W. ; Egdell ; R.G.
• 关键词：Low index single crystal surfaces ; Scanning tunnelling microscopy ; Surface defects ; Synchrotron radiation photoelectron spectroscopy ; Tungsten oxide ; Visible and ultraviolet photoelectron spectroscopy
• 刊名：Surface Science
• 出版年：2000
• 出版时间：July 20, 2000
• 年：2000
• 卷：460
• 期：1-3
• 页码：277-291
• 全文大小：729 K

文摘

Scanning tunnelling microscopy has been used to identify a number of surface reconstructions on the (001) surface of the cubic metallic sodium tungsten bronze, Na_0.667WO₃. Which is dominant has been found to depend critically on sample preparation. As well as a (√2×√2)R45° reconstruction that bears a striking similarity to that of the parent material, tungsten trioxide, regions of (2×1) periodicity are observed that can only be explained in terms of an Na_yO surface layer. In the current work, we relate the effect of sample preparation on the surface electronic structure of Na_0.667WO₃(001) with that on the atomic structure by comparing photoemission spectra with STM images. Particular interest is focused on band gap defect states in photoemission spectra which, in contrast to similar states in spectra from WO₃, do not appear to correlate with the appearance of localised defects or highly reduced terraces in STM images. The existence of peroxide-like oxygen dimers at the (2×2) reconstructed surface, on the other hand, is characterised by the appearance of identifiable states in the valence band spectrum.