Tunable sources of X-ray radiation are widely used for imaging and spectroscopy in fundamental science, medicine and industry. The growing demand for highly tunable, high-brightness laboratory-scale X-ray sources motivates research into new fundamental mechanisms of X-ray generation. Here, we demonstrate the ability of van der Waals materials to serve as a platform for tunable X-ray generation when irradiated by moderately relativistic electrons available, for example, from a transmission electron microscope. The radiation spectrum can be precisely controlled by tuning the acceleration voltage of the incident electrons, as well as by our proposed approach: adjusting the lattice structure of the van der Waals material. We present experimental results for both methods, observing the energy tunability of X-ray radiation from the van der Waals materials WSe₂, CrPS₄, MnPS₃, FePS_3, CoPS₃ and NiPS₃. Our findings demonstrate the concept of material design at the atomic level, using van der Waals heterostructures and other atomic superlattices, for exploring novel phenomena of X-ray physics.

X射线辐射的可调源广泛用于基础科学，医学和工业中的成像和光谱学。对高度可调，高亮度实验室规模X射线源的需求不断增长，这激发了人们对X射线产生的新基本机制的研究。在这里，我们展示了范德华材料在受到中等相对论电子（例如，透射电子显微镜）照射时，可作为可调X射线生成平台的能力。可以通过调整入射电子的加速电压以及我们提出的方法来精确控制辐射光谱：调整范德华材料的晶格结构。我们提供两种方法的实验结果，₂，CrPS ₄，MnPS ₃，FePS _3， CoPS ₃和NiPS ₃。我们的发现证明了利用范德华力异质结构和其他原子超晶格在原子水平上进行材料设计的概念，以探索X射线物理学的新颖现象。