Gearless two-crystal x-ray spectrometer for chemical state analysis

Abstract

A two-crystal spectrometer for chemical state analysis of high-resolution x-ray fluorescence spectra employs ball-screw and slide mechanisms rather than gears to obtain a 2θ scanning range of 40°–147° and a Δ2θ scanning step of 10−4 deg under vacuum, and a 2θ resolution of 10−4 deg in determination of an intercrystal angle with encoder-based measurement and servomechanical control of position. The spectrometer, although simple in structure, is a powerful instrument for chemical state analysis, as demonstrated by its high resolution, stability, and repeatability in determination of the Kα lines of first transition metals, aluminum, silicon, and sulfur with Si(220), ADP(101), InSb(111), and Ge(111) as analyzer crystal, respectively.