Development of a compact beam intensity monitor for micro X-ray absorption fine structure measurements

A compact beam intensity monitor detecting an X-ray excited sample current from a thin metal foil was developed for micro X-ray absorption fine structure (XAFS) measurements. By utilizing gas amplification caused by the ejected photoelectrons or Auger electrons, the monitor can achieve better sensitivity than what can be realized with the ionization chamber. Fluctuation of the beam intensity through the pinhole of 10 μm was precisely measured by using this monitor, and the XAFS spectrum from a Ni thin foil was successfully measured with adequate normalization.