Liao Shusen, Zhu Yunxuan, Ye Qian, Sanders Stephen, Yang Jiawei, Alabastri Alessandro, Natelson Douglas
Applied Physics Graduate Program, Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States.
Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States.
J Phys Chem Lett. 2023 Aug 24;14(33):7574-7580. doi: 10.1021/acs.jpclett.3c01948. Epub 2023 Aug 17.
Surface-enhanced Raman spectroscopy (SERS) is enabled by local surface plasmon resonances (LSPRs) in metallic nanogaps. When SERS is excited by direct illumination of the nanogap, the background heating of the lattice and electrons can prevent further manipulation of the molecules. To overcome this issue, we report SERS in electromigrated gold molecular junctions excited remotely: surface plasmon polaritons (SPPs) are excited at nearby gratings, propagate to the junction, and couple to the local nanogap plasmon modes. Like direct excitation, remote excitation of the nanogap can generate both SERS emission and an open-circuit photovoltage (OCPV). We compare the SERS intensity and the OCPV in both direct and remote illumination configurations. SERS spectra obtained by remote excitation are much more stable than those obtained through direct excitation when the photon count rates are comparable. By statistical analysis of 33 devices, the coupling efficiency of remote excitation is calculated to be around 10%, consistent with the simulated energy flow.
表面增强拉曼光谱（SERS）由金属纳米间隙中的局域表面等离子体共振（LSPR）实现。当通过纳米间隙的直接照明激发SERS时，晶格和电子的背景加热会阻碍对分子的进一步操控。为克服这一问题，我们报道了在电迁移金分子结中通过远程激发实现的SERS：表面等离激元极化激元（SPP）在附近的光栅处被激发，传播到结处，并耦合到局部纳米间隙等离子体模式。与直接激发一样，纳米间隙的远程激发既可以产生SERS发射，也可以产生开路光电压（OCPV）。我们比较了直接照明配置和远程照明配置下的SERS强度和OCPV。当光子计数率相当时，通过远程激发获得的SERS光谱比通过直接激发获得的光谱稳定得多。通过对33个器件的统计分析，计算出远程激发的耦合效率约为10%，与模拟的能量流一致。
