SILICON PHOTODIODE DETECTOR FOR A GLANCING-EMERGENCE-ANGLE EXAFS TECHNIQUE

We have constructed a silicon photodiode detector for use with a glancing-emergence-angle (GEA) geometry useful for obtaining fluorescence EXAFS spectra from thick specimens with concentrated absorbing species. We present a description of the detector and the results of tests, including dark-noise tests, EXAFS spectra from a standard sample, and a comparison to an ion chamber also in the GEA configuration. Data obtained from the two detectors are comparable in quality, making the diode detector a preferable choice for this application due to factors such as simplicity of construction and compact size. The diodes also have potential for significant further improvement in the quality of the signal due to their high quantum efficiency if the dark noise can be reduced. We present suggestions for achieving this in future generations of the detector.