可视化与量化由空间分辨原子干涉主导的原子对拉曼强度的贡献

中文摘要 AI 辅助

拉曼光谱通常被简化为分子指纹传感，却忽略了拉曼强度。原子拉曼强度贡献将拉曼强度追溯至其微观起源，可作为局域电子结构的描述子，但目前仍缺乏一种兼具物理合理性且直观的框架。因此，本研究结合了分解拉曼强度的两条主要路线：原子拉曼张量与原子拉曼强度密度（RIDs）。前者用于定义原子拉曼强度，该强度可量化每个原子对整体拉曼信号贡献的大小与相位，研究表明弱拉曼谱带可能源于多个单独较强的原子贡献发生相消干涉。后者基于重新定义的原子拉曼极化率密度（RPDs），并参照原子拉曼强度进行定义，可展示单个原子的运动如何调制整个分子的极化率，原子RIDs因此能呈现不同原子贡献的局域干涉，它们积分后得到原子拉曼强度，实现了两条主要路线的衔接。额外的（原子）电荷密度差（CDDs）将RIDs扩展至电子结构效应。最后，将该方法应用于取代2-巯基苯并噻唑衍生物的实验表面增强拉曼光谱，并讨论取代基诱导的拉曼强度变化，研究表明此类变化未必源于全局极化率改变，而是源于原子贡献相对相位的变化。该方法不仅限于SERS，还广泛适用于各类拉曼、SERS或皮腔TERS实验，为原子级分辨研究吸附、催化及化学反应等分子过程提供了基础。

英文摘要

Raman spectroscopy is commonly reduced to molecular fingerprint sensing, neglecting Raman intensities. Atomic Raman intensity contributions trace Raman intensities back to their microscopic origin and act as local electronic structure descriptors; however, a both physical but intuitive framework is missing by now. Therefore, in this work, we combine the two main lines of decomposing Raman intensities: atomic Raman tensors and atomic Raman Intensity Densities (RIDs). The former are used to define atomic Raman intensities which quantify both the magnitude and the phase of each atom's contribution to the global Raman signal, demonstrating that weak Raman bands may arise from destructive interference of individually strong atomic contributions. The latter build on redefined atomic Raman Polarizability Densities, RPDs, and are defined in analogy to our atomic Raman intensities. They show how the motion of an individual atom modulates the polarizability of the entire molecule. Atomic RIDs thus show local interferences of different atomic contributions. They integrate to the atomic Raman intensities bridging the two main lines. Additional (atomic) Charge Density Differences (CDDs) extend the RIDs to electronic structure effects. Finally, we apply the methodology to experimental surface-enhanced Raman spectra of substituted 2-mercaptobenzothiazole derivatives and discuss substituent-induced Raman intensity changes. We show that such changes do not necessarily stem from globally altered polarizabilities but from changes in the relative phase of atomic contributions. However, this method is not limited to SERS but widely applicable to all kinds of Raman, SERS or picocavity TERS experiments offering a basis for atomically resolved investigations of molecular processes such as adsorption, catalysis, and chemical reactions

发表机构

• University of Tübingen（蒂宾根大学）
• Madrid Institute for Advanced Studies, IMDEA Nanoscience（马德里高级研究所，IMDEA纳米科学）

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