Plasmonic metal nanostructures can concentrate incident optical fields in nanometer-sized volumes, called hot spots. This leads to enhanced optical responses of molecules in such a hot spot but also to chemical transformations, driven by plasmon-induced hot carriers. Here, we employ tip-enhanced Raman spectroscopy (TERS) to study the mechanism of these reactions in situ at the level of a single hot spot. Direct spectroscopic measurements reveal the energy distribution of hot electrons, as well as the temperature changes due to plasmonic heating. Therefore, charge-driven reactions can be distinguished from thermal reaction pathways. The products of the hot-carrier-driven reactions are strikingly similar to the ones known from X-ray or e-beam-induced surface chemistry despite the >100-fold energy difference between visible and X-ray photons. Understanding the analogies between those two scenarios implies new strategies for rational design of plasmonic photocatalytic reactions and for the elimination of photoinduced damage in plasmon-enhanced spectroscopy.

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等离子体驱动的光催化导致电子束和X射线诱导的表面化学的已知产品

等离子体金属纳米结构可以将入射光场集中在纳米大小的体积（称为热点）中。这导致在这种热点中分子的光学响应增强，但也导致了由等离激元诱导的热载体驱动的化学转化。在这里，我们采用尖端增强拉曼光谱（TERS）在单个热点水平上研究这些反应的原位机理。直接光谱测量揭示了热电子的能量分布，以及由于等离激元加热引起的温度变化。因此，可以将电荷驱动的反应与热反应路径区分开。尽管在可见光和X射线光子之间的能量差> 100倍，但热载流子驱动反应的产物与从X射线或电子束诱导的表面化学已知的产物惊人地相似。