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As a project for the experimental station's upgrade, we ordered _a fluorescent ion chamber apparatus from US which has good performance and lower price compared with the scintillation or semiconductor detectors. The XAFS group developed a NIM V/F module for the system, solved several problems such as bias voltage supply, noise introduced by gas flow and null setting of the amplifier, and made the system reach its best status under the current beam condition.
During the SR dedicated run in September, 1994 , with the fluorescent apparatus two research projects including metal-protein structure and a kind of catalyst structure were successfully carried out which haven't been solved with transmission method for a long time at this station. A series of data were collected for further analysis. Figure 1 shows the collected Zn(0.05%) K edge XAFS spectrum of the metal protein sample.
The setting up of the fluorescent XAFS method allows the testing limit for the dilute sample to extend 2-3 order of magnitude (reached 0.05%) and opens new structure research fields in the biology and material science at BSRF XAFS station.
Xie Yaning ---------------------------------------------------------------------
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Febrary 1995 BEPC News