AI 中文总结
研究二维范德华材料深度分辨表征难题，利用驻波光电子发射显微镜对单层WS2进行埃级光谱显微镜研究，通过调整X射线驻波获取化学深度剖面等，测量出硫衍生价带光谱权重偏移，确立该方法为非破坏性深度分辨探针。
AI 中文摘要
二维范德华材料在电子、光电子和量子技术方面具有潜力，但深度分辨表征具有挑战性。本文展示了用于W/C多层衬底上单层WS2埃级光谱显微镜的驻波光电子发射显微镜（SW-PEEM）。通过单层调整X射线驻波可得到化学深度剖面和价带调制，对顶部和底部硫层具有更高灵敏度。X射线光学建模确定结构和场分布。测量显示顶部和底部硫层增强灵敏度测量之间硫衍生价带光谱权重有~0.2 eV的偏移。此偏移不太可能源于强直接衬底杂化，而是与硫相关表面物种一致。这些结果确立了SW-PEEM作为非破坏性深度分辨探针，突出其在探测范德华和莫尔系统中界面耦合、化学重构和新兴态方面的潜力。
英文摘要
Two-dimensional van der Waals materials promise electronic, optoelectronic, and quantum technologies, yet depth-resolved characterization remains challenging. Here, we demonstrate standing-wave photoemission electron microscopy (SW-PEEM) for Angstrom-scale spectromicroscopy of monolayer WS2 on a W/C multilayer substrate. Tuning the X-ray standing wave through the monolayer yields a chemical depth profile and valence-band modulation with enhanced sensitivity to the top and bottom sulfur layers. X-ray optical modeling determines the structure and field distribution. The measurements reveal an ~0.2 eV shift in sulfur-derived valence-band spectral weight between measurements with enhanced sensitivity to the top and bottom sulfur layers. This shift is unlikely to arise from strong direct substrate hybridization and is instead consistent with sulfur-related surface species, as supported by calculations using a representative elemental-sulfur model. These results establish SW-PEEM as a non-destructive depth-resolved probe, highlighting its potential to probe interfacial coupling, chemical reconstruction, and emergent states in van der Waals and moiré systems.
