Compact fluorescence x-ray detector for surface EXAFS and x-ray standing wave measurements

Abstract

The design and performance of a compact, ultrahigh vacuum (UHV) compatible x-ray detector is described which can be applied to measurements of surface EXAFS spectra and x-ray standing wave (SW) profiles. The detector is a type of gas flow proportional counter. Its compactness allows us to save space around the sample. A 25-μm-thick beryllium window separates UHV (<1×10−10 mbar) environment from atmospheric pressure and provides good efficiency to detect low energy x rays. Surface EXAFS spectra of less than 0.1 monolayer chlorine on a Ni substrate are successfully measured with high quality. Its high signal-to-background ratio allows us to measure SW profiles, which could hardly be obtained with any electron yield detection technique.