Laboratory EXAFS Spectrometer, Principles and Applications

Abstract

In order to be independent of poor availability of synchrotron beamtime a laboratory EXAFS spectrometer has been developed. The X-ray source is a rotating anode generator (max. voltage 60 kV, max. current 300 mA). Monochromatisation and focusing is done with a linear spectrometer, based upon the Rowland circle geometry and a silicon crystal monochromator. High positioning accuracy of monochromator and sample stages are achieved by computer control and position feedback with magnetic rulers. Ionisation chambers monitor incoming and transmitted flux.The spectra of Pt and Na{2}Pt(OH){6} and their Fourier transforms are compared with the same data taken at SSRL, Stanford (USA). The influence of the resolution on the Fourier transforms has been investigated. The applicability of the apparatus is demonstrated with 6 wt% Bi in LaPO{4} of which the oxygen coordination has been compared to that of Bi in BiPO{4}. As a second example data of Platinum metal particles in ZSM-5 catalyst are presented.