Kukk Edwin, Vacheresse Regis, Ismail Iyas, Marchenko Tatiana, Guillemin Renaud, Piancastelli Maria Novella, Simon Marc, Travnikova Oksana
Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland.
Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris, France.
J Synchrotron Radiat. 2025 Jul 1;32(Pt 4):1017-1027. doi: 10.1107/S1600577525004862. Epub 2025 Jun 23.
The MUSTACHE setup (MUlti-STep photofragmentation studies by Auger electron-ion Coincidences using High Energy photons) is a high-resolution electron-multi-ion coincidence system optimized for gas-phase experiments in the tender (∼2-10 keV) and hard (>5 keV) X-ray range. The system integrates a high-resolution hemispherical electron analyzer with a Wiley-McLaren-type ion time-of-flight (TOF) spectrometer, enabling coincidence measurements of Auger electrons and high-energy photoelectrons. Designed to overcome challenges in high-energy electron detection while maintaining excellent energy resolution, the setup covers a broad kinetic energy range up to 5 keV, allowing investigation of hard-X-ray-induced Auger cascades in molecules containing high-Z elements, where initial fluorescence decay is followed by Auger processes within this 5 keV detection window. The ion TOF spectrometer provides high-resolution ion mass and momentum analysis, essential for studying light and fast ions generated by deep-core ionization. System capabilities are demonstrated through test measurements on benchmark atomic and molecular systems, such as argon, nitrogen and carbon disulfide. These measurements demonstrate energy-resolved high-kinetic-energy photoelectron-ion coincidences and momentum-resolved multi-ion coincidences following deep-core ionization and Coulomb explosion. MUSTACHE enables investigations into deep-core ionization, Auger cascade processes and Coulomb explosion dynamics in isolated gas-phase species, offering insights into fundamental ionization and fragmentation processes. These results demonstrate that the MUSTACHE setup is a powerful tool for high-resolution electron-ion coincidence spectroscopy, extending advanced coincidence techniques into the hard X-ray regime and providing unprecedented opportunities for studying high-energy X-ray-induced phenomena.
MUSTACHE装置（利用高能光子通过俄歇电子 - 离子符合技术进行的多步光解离研究）是一种高分辨率电子 - 多离子符合系统，针对软X射线（约2 - 10 keV）和硬X射线（>5 keV）范围内的气相实验进行了优化。该系统将高分辨率半球形电子分析仪与威利 - 麦克拉伦型离子飞行时间（TOF）光谱仪集成在一起，能够对俄歇电子和高能光电子进行符合测量。该装置旨在克服高能电子检测中的挑战，同时保持出色的能量分辨率，其覆盖的动能范围高达5 keV，可用于研究含高Z元素分子中硬X射线诱导的俄歇级联过程，在这个5 keV检测窗口内，初始荧光衰变之后是俄歇过程。离子TOF光谱仪提供高分辨率的离子质量和动量分析，这对于研究深芯电离产生的轻离子和快离子至关重要。通过对基准原子和分子系统（如氩气、氮气和二硫化碳）的测试测量展示了系统的性能。这些测量展示了深芯电离和库仑爆炸后能量分辨的高动能光电子 - 离子符合以及动量分辨的多离子符合。MUSTACHE能够对孤立气相物种中的深芯电离、俄歇级联过程和库仑爆炸动力学进行研究，深入了解基本的电离和碎片化过程。这些结果表明，MUSTACHE装置是高分辨率电子 - 离子符合光谱学的强大工具，将先进的符合技术扩展到硬X射线领域，并为研究高能X射线诱导的现象提供了前所未有的机会。
