ABSTRACT
Arsenic K-edge XANES spectra were recorded from model compounds and samples at Beamline 20B Australian National Beamline Facility (ANBF) Photon Factory, KEK, Tsukuba, Japan. The spectra were recorded at room temperature in fluorescence mode using a thirty-six-element germanium-array detector. BL-20B was equipped with a channel-cut Si(111) monochromator which was detuned 50% to reject harmonics. Sodium arsenate was used as an internal standard for energy calibration, with the first peak of the first derivative assumed to be 11,873.6 eV. Solid models diluted in boron nitride (ground to <20 μm) were pressed into aluminium spacers then covered between two 63.5 μm Kapton tape windows (window size, 2*10 mm). Data analysis, including calibration, averaging and background subtraction of all spectra and Principal Component Analysis (PCA), target and linear regression analyses of XANES spectra were performed using the EXAFSPAK software package (George and Pickering 2000). The precision of fitting was determined to be ∼10% based on analyses of control model compound mixtures.
