Optimizing hot electron generation is important for increasing the efficiency of light harvesting in photovoltaics and photocatalysis. Surface-enhanced Raman spectroscopy (SERS) is a valuable tool to assess the extent of such electron production as it enables monitoring of the hot electron-driven chemical reactions. In this work, SERS was used to compare the hot electrons generated when two localized surface plasmon resonance (LSPR) modes present in plasmonic substrates prepared using silver nanocubes (AgNC) were excited: the dipole LSPR mode and the coupled LSPR mode. The silver plasmonic monolayers were prepared on polystyrene-coated glass slides at various nanoparticle densities and therefore varying intensities of the dipolar and coupled resonances. Dehalogenation of bromothiophenol and chlorothiophenol was used as a hot electron sensitive reaction. The dependence of the reaction yield on the excitation wavelength, power, and extent of plasmonic coupling was assessed by monitoring SERS spectral evolution. It was found that excitation of the dipole mode resulted in a hot electron yield higher than that of the coupling mode for the substrates used. Additionally, it was found that the hot electron yield for the AgNC substrates decreased as the coupling mode strength increased. This work shows the need for a better control over the plasmonic substrate fabrication and characterization methods to allow improved hot electron generation from the coupled modes.

中文翻译：

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SERS 监测等离子银纳米立方单层中热电子的产生


优化热电子产生对于提高光伏和光催化中的光收集效率非常重要。表面增强拉曼光谱 (SERS) 是评估此类电子产生程度的重要工具，因为它能够监测热电子驱动的化学反应。在这项工作中，SERS 用于比较使用银纳米立方体 (AgNC) 制备的等离子体基底中存在的两种局域表面等离子体共振 (LSPR) 模式被激发时产生的热电子：偶极 LSPR 模式和耦合 LSPR 模式。银等离子体单层是在聚苯乙烯涂层的载玻片上以不同的纳米颗粒密度制备的，因此偶极和耦合共振的强度也不同。溴苯硫酚和氯苯硫酚的脱卤被用作热电子敏感反应。通过监测 SERS 光谱演化来评估反应产率对激发波长、功率和等离子体耦合程度的依赖性。发现偶极子模式的激发导致的热电子产率高于所用基板的耦合模式。此外，还发现 AgNC 基底的热电子产额随着耦合模式强度的增加而降低。这项工作表明需要更好地控制等离子体衬底制造和表征方法，以改善耦合模式的热电子生成。