Understanding, predicting, and controlling plasmon–molecule energy transfer are important for improvements to plasmonic photocatalysis and photothermal therapies. Here, we use continuous wave surface-enhanced anti-Stokes and Stokes Raman spectroscopy to quantify the vibrational kinetic energy, equivalent to a molecular temperature under a Boltzmann approximation, of Raman-active vibrational modes of molecules at plasmonic interfaces. In previous work from our group, we observed an anomalous steady-state reduction in vibrational kinetic energies in benzenethiols absorbed onto the surface of gold nanoparticles. To further explore this effect, here, we quantify the wavelength dependence of vibrational energy in plasmon–fluorophore systems, where molecules can undergo electronic transitions with resonant excitation. We used three excitation wavelengths and three molecules with varying electronic resonance energies. We observe wavelength-dependent vibrational energy distributions, which we attribute to competing effects of on-resonance heating and off-resonance decrease in the population ratio. This work thus quantifies the resonance wavelength dependence of vibrational energy in plasmon molecular systems and helps to suggest future applications of tailored systems with controllable energy transfer pathways.

中文翻译：

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荧光团-等离子体系统中等离子体激元引起的振动能量转移的波长依赖性


理解、预测和控制等离激元分子能量转移对于改进等离激元光催化和光热疗法非常重要。在这里，我们使用连续波表面增强反斯托克斯和斯托克斯拉曼光谱来量化等离子体界面分子拉曼活性振动模式的振动动能，相当于玻尔兹曼近似下的分子温度。在我们小组之前的工作中，我们观察到吸附在金纳米颗粒表面的苯硫酚的振动动能出现异常稳态降低。为了进一步探索这种效应，我们在这里量化了等离子荧光团系统中振动能量的波长依赖性，其中分子可以在共振激发下经历电子跃迁。我们使用了三种激发波长和三种具有不同电子共振能量的分子。我们观察到与波长相关的振动能量分布，我们将其归因于共振加热和非共振布居比下降的竞争效应。因此，这项工作量化了等离子体分子系统中振动能量的共振波长依赖性，并有助于建议具有可控能量转移途径的定制系统的未来应用。