<p>Researchers at the European XFEL have developed a new measuring device for hard X-ray light, known as a Laue spectrometer. It can detect photon energies over 15 kiloelectronvolts with high precision and improved efficiency. This is important for the study of technologically significant materials, such as those capable of transporting electricity without loss or enhancing the efficiency of chemical processes.</p><p>Traditional X-ray spectrometers operate in the Bragg geometry, where X-rays are bent by parallel atom planes, similar to mirrors reflecting visible light. However, at high energies, much of the hard X-ray light passes through the crystal unused, reducing the performance of conventional spectrometers. The new Laue spectrometer developed at the FXE experimental station at the European XFEL addresses this issue by working in the Laue geometry, where X-rays pass through the crystal and are bent by atomic layers perpendicular to the surface. This makes the new Laue analyzer more efficient at higher X-ray energies.</p><p>The newly developed device, called the High Energy Laue X-ray Emission Spectrometer (HELIOS), is now available to all users at the European XFEL. It offers an extremely high precision of about 1.2 x 10^-4 at a photon energy of about 18.6 keV, reaching 4 to 22 times higher signal strength compared to conventional spectrometers. This allows the detection of particularly interesting electronic transitions in so-called 4d-transition metals, which are otherwise very difficult to measure.</p>