Vacuum Formed Temporary Spherical and Toroidal Bent Crystal Analyzers for High Resolution X-ray Spectroscopy

TL;DR

This paper introduces a flexible, vacuum-forming method to create temporary, high-resolution spherically and toroidally bent crystal analyzers for X-ray spectroscopy, enabling quick exchange and customization for various applications.

Contribution

The study presents a novel vacuum forming technique for creating temporary bent crystal analyzers without adhesives, offering enhanced flexibility for spectrometer configurations.

Findings

Achieved ~1-eV energy resolution with vacuum-formed analyzers.

Demonstrated effective use in XAFS and XES measurements.

Showed the analyzers can be easily exchanged and customized.

Abstract

We demonstrate that vacuum forming of 10-cm diameter silicon wafers of various crystallographic orientations under an x-ray permeable, flexible window can easily generate spherically bent crystal analyzers (SBCA) and toroidally bent crystal analyzers (TBCA) with ~1-eV energy resolution and a 1-m major radius of curvature. In applications at synchrotron light sources, x-ray free electron lasers, and laboratory spectrometers these characteristics are generally sufficient for many x-ray absorption fine structure (XAFS), x-ray emission spectroscopy (XES), and resonant inelastic x-ray scattering (RIXS) applications in the chemical sciences. Unlike existing optics manufacturing methods using epoxy or anodic bonding, vacuum forming without adhesive is temporary in the sense that the bent wafer can be removed when vacuum is released and exchanged for a different orientation wafer. Therefore, the combination of an x-ray compatible vacuum-forming chamber, a library of thin wafers, and a small number of forms having different secondary curvatures can give extreme flexibility in spectrometer energy range. As proof of this method we determine the energy resolution and reflectivity for several such vacuum-formed bent crystal analyzers (VF-BCA) in laboratory based XAFS and XES studies using a conventional x-ray tube. For completeness we also show x-ray images collected on the detector plane to characterize the resulting focal spots and optical aberrations.