Zoltowski Chelsea M, Shoup Deben N, Schultz Zachary D
Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.
J Phys Chem C Nanomater Interfaces. 2022 Sep 1;126(34):14547-14557. doi: 10.1021/acs.jpcc.2c03150. Epub 2022 Aug 23.
The excitation of plasmon resonances on nanoparticles generates locally enhanced electric fields commonly used for sensing applications and energetic charge carriers can drive chemical transformations as photocatalysts. The surface-enhanced Raman scattering (SERS) spectra from mercaptobenzoic acid (MBA) adsorbed to gold nanoparticles (AuNP) and silica encapsulated gold nanoparticles (AuNP@silica) can be used to assess the impact of energetic charge carriers on the observed signal. Measurements were recorded using a traditional point focused Raman spectroscopy and a wide-field spectral imaging approach to assess changes in the spectra of the different particles at increasing power density. The wide-field approach provides an increase in sampling statistics and shows evidence of SERS frequency fluctuations from MBA at low power densities, where it is commonly difficult to record spectra from a point focused spot. The increased spectral resolution of the point spectroscopy measurement provides improved peak identification and the ability to correlate the frequency fluctuations to charged intermediate species. Interestingly, our work suggests that isolated nanoparticles may undergo frequency fluctuations more readily than aggregates.
纳米颗粒上等离子体共振的激发会产生局部增强的电场，常用于传感应用，而高能电荷载流子可作为光催化剂驱动化学转化。吸附在金纳米颗粒（AuNP）和二氧化硅包裹的金纳米颗粒（AuNP@二氧化硅）上的巯基苯甲酸（MBA）的表面增强拉曼散射（SERS）光谱可用于评估高能电荷载流子对观测信号的影响。测量使用传统的点聚焦拉曼光谱和宽场光谱成像方法进行，以评估不同颗粒在功率密度增加时光谱的变化。宽场方法增加了采样统计量，并显示出在低功率密度下MBA的SERS频率波动的证据，在低功率密度下通常很难从点聚焦光斑记录光谱。点光谱测量提高的光谱分辨率提供了更好的峰识别能力，并能够将频率波动与带电中间物种相关联。有趣的是，我们的工作表明，孤立的纳米颗粒可能比聚集体更容易发生频率波动。
