Improvement in XAFS beamline BL01B1 at SPring-8

Abstract

Beamline BL01B1 was constructed for conventional XAFS measurements using a bending magnet light source at SPring-8 in 1997 [1]. BL01B1 covers a wide energy range from 3.8 to 113 keV using an adjustable inclined double-crystal monochromator and a double mirror system. Here, we describe a newly developed apparatus and the current status of the BL01B1. A time-efficient QEXAFS method was developed to measure high quality spectra up to high-k regions in the shortest possible time. The method involves sweeping the monochromator continuously at a variable angular speed depending on the k-region using a VME stepping motor controller. During scanning, a pair of crystals of the monochromator rotates without translation motion like a channel-cut crystal. This QEXAFS method was applied to the fluorescence mode using a 19-element Ge detector combined with a digital X-ray processor system. A new conversion electron yield detector having a rotational sample stage was developed for single crystalline samples. Angular oscillations of 4 degrees in the sample rotation stage around the axis normal to the sample surface successfully remove diffraction noise in the XAFS spectra.