# Experimental determination of line energies, line widths and relative transition probabilities of the Gadolinium L X-ray emission spectrum

## TL;DR

This study precisely measured the energies, widths, and transition probabilities of gadolinium's L X-ray emission spectrum using synchrotron radiation and a custom spectrometer, revealing deviations from existing data and identifying satellite lines.

## Contribution

The paper provides the first comprehensive experimental determination of gadolinium's L X-ray line parameters with high accuracy, including the detection of satellite lines and comparison with existing databases.

## Key findings

- Significant deviations found in Lγ2 and Lγ3 line data compared to databases.
- Identification of two satellite lines near Lβ2,15 and Lγ1 emissions.
- High-precision calibration of the spectrometer using elastically scattered photons.

## Abstract

In this work the complete L-emission spectrum of gadolinium with respect to line energies, natural line widths, and relative transition probabilities was investigated using monochromatized synchrotron radiation. The measurements were realized in the PTB laboratory at BESSY II by means of an in-house built von Hamos spectrometer based on up to two full-cylinder HAPG mosaic crystal. The von Hamos spectrometer is calibrated by means of elastically scattered photons from the employed synchrotron radiation beamline leading to a well-defined energy scale and an experimentally determined spectrometer response. A selective excitation of the gadolinium L subshells was carried out to ensure a robust deconvolution of neighboring emission lines of different L subshells. The experimental results are discussed in the context of existing data from common databases and published values since significant deviations, especially for the L$\gamma_2$ and L$\gamma_3$ emission lines, are observed. We further substantiate and discuss two satellite lines at the low-energy side of the L$\beta_{2,15}$ and L$\gamma_1$ emission lines arising from the N$_{4,5}$ subshell.