Wang Chih-Feng, O'Callahan Brian T, Kurouski Dmitry, Krayev Andrey, El-Khoury Patrick Z
Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
Earth and Biological Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
J Phys Chem Lett. 2020 May 21;11(10):3809-3814. doi: 10.1021/acs.jpclett.0c01006. Epub 2020 Apr 30.
We revisit the reductive coupling of nitrothiophenol (NTP) to form dimercaptoazobenzene (DMAB), herein monitored through gap-mode tip-enhanced Raman spectroscopy (TERS) and nanoimaging. We employ a plasmonic Au probe (100 nm diameter at its apex) illuminated with a 633 nm laser source (50 μW/μm at the sample position) to image an NTP-coated faceted silver nanoparticle (∼70 nm diameter). A detailed analysis of the recorded spectra reveals that anionic NTP species contribute to the recorded spectral images, in addition to the more thoroughly described DMAB product. Notably, the signatures of the anions are more pronounced than those of the DMAB product under our present experimental conditions. Our results thus demonstrate that anions and their spectral signatures must be considered in the analysis of plasmon-enhanced optical spectra and images.
我们重新审视了硝基硫酚（NTP）还原偶联形成二巯基偶氮苯（DMAB）的过程，在此通过间隙模式尖端增强拉曼光谱（TERS）和纳米成像进行监测。我们使用一个等离子体金探针（尖端直径为100 nm），用633 nm激光源（在样品位置为50 μW/μm）照射，以成像一个涂有NTP的多面银纳米颗粒（直径约70 nm）。对记录光谱的详细分析表明，除了已被更充分描述的DMAB产物外，阴离子型NTP物种也对记录的光谱图像有贡献。值得注意的是，在我们目前的实验条件下，阴离子的特征比DMAB产物的特征更明显。因此，我们的结果表明，在分析等离子体增强光谱和图像时，必须考虑阴离子及其光谱特征。
