Selective x-ray Bragg spectrometry: Optimizing fluorescence microprobe sensitivity for precious metals

Abstract

This instrument development project was aimed at developing an x-ray spectrometer configuration for the x-ray fluorescence microprobe optimized for the detection of precious metals in geological and biological samples with the objective of improving detection limits and reducing interference from major elements and the scattered beam. The approach used Bragg diffraction from a surface shaped to a log-spiral to focus x-rays of a particular energy onto a solid-state detector. The result is an enhancement of the precious metal lines within the relatively narrow bandpass of the Bragg crystal surface and suppression of interfering elements and detector artefacts, such as tailing and escape peaks ..