Ward Daniel R, Grady Nathaniel K, Levin Carly S, Halas Naomi J, Wu Yanpeng, Nordlander Peter, Natelson Douglas
Department of Physics and Astronomy, Applied Physics Graduate Program, Rice University, 6100 Main Street, Houston, Texas 77005, USA.
Nano Lett. 2007 May;7(5):1396-400. doi: 10.1021/nl070625w. Epub 2007 Apr 13.
Single-molecule detection with chemical specificity is a powerful and much desired tool for biology, chemistry, physics, and sensing technologies. Surface-enhanced spectroscopies enable single-molecule studies, yet reliable substrates of adequate sensitivity are in short supply. We present a simple, scaleable substrate for surface-enhanced Raman spectroscopy (SERS) incorporating nanometer-scale electromigrated gaps between extended electrodes. Molecules in the nanogap active regions exhibit hallmarks of very high Raman sensitivity, including blinking and spectral diffusion. Electrodynamic simulations show plasmonic focusing, giving electromagnetic enhancements approaching those needed for single-molecule SERS.
具有化学特异性的单分子检测是生物学、化学、物理学和传感技术领域一种强大且备受期待的工具。表面增强光谱技术使单分子研究成为可能，但具有足够灵敏度的可靠底物却供不应求。我们展示了一种用于表面增强拉曼光谱（SERS）的简单、可扩展的底物，该底物在延伸电极之间包含纳米级电迁移间隙。纳米间隙活性区域中的分子表现出极高拉曼灵敏度的特征，包括闪烁和光谱扩散。电动力学模拟显示了等离子体聚焦，电磁增强接近单分子SERS所需的增强程度。
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