Resonant inelastic x-ray scattering spectrometer with 25 meV resolution at Cu K-edge

TL;DR

This paper reports a highly precise inelastic x-ray scattering spectrometer at the Cu K-edge achieving 25 meV resolution, enabling detailed phonon measurements in materials.

Contribution

The development of a novel spectrometer with unprecedented energy resolution using segmented quartz analyzer and advanced optics.

Findings

Achieved 25 meV resolution at 8981 eV energy.

Successfully measured phonon dispersion in beryllium.

Resolution matched ray tracing simulations.

Abstract

An unparalleled resolution is reported with an inelastic x-ray scattering instrument at the Cu K-edge. Based on a segmented concave analyzer, featuring single crystal quartz (SiO_{2}) pixels, the spectrometer delivers a resolution near 25 meV (FWHM) at 8981 eV. Besides the quartz analyzer, the performance of the spectrometer relies on a four-bounce Si(553) high-resolution monochromator and focusing Kirkpatrick-Baez optics. The measured resolution agrees with the ray tracing simulation of an ideal spectrometer. We demonstrated the performance of the spectrometer by reproducing the phonon dispersion curve of a beryllium (Be) single crystal.