Charge Transfer Enhancement in the SERS of a Single Molecule

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• 作者：Won-Hwa Park ; Zee Hwan Kim
• 刊名：Nano Letters
• 出版年：2010
• 出版时间：October 13, 2010
• 年：2010
• 卷：10
• 期：10
• 页码：4040-4048
• 全文大小：634K
• 年卷期：v.10,no.10(October 13, 2010)
• ISSN：1530-6992

文摘

We measured the surface-enhanced Raman scattering (SERS) of individual gold nanoparticle-4-aminobenzenethiol (ABT)-gold film junctions to investigate the charge-transfer (CT) enhancement of the SERS signals. Despite the mild electromagnetic field enhancement (10⁵) and high surface density of the ABT-molecules (240 molecules/hotspot) at the junctions, we observed the clear spectral and temporal signatures of CT-enhanced single-molecule SERS (SM-SERS). The result reveals that only a small fraction of the molecules at the junction has a significant CT-enhancement of 10¹10³, whereas the rest of the molecules are nearly CT-inactive. Furthermore, the result also proves that overall (charge-transfer and electromagnetic) enhancement of 10⁶10⁸ is sufficient to observe the SM-SERS of an electronically off-resonant molecule, which disproves the widespread belief that a minimum enhancement of 10¹⁴ is required for SM-SERS.

Keywords:

Surface plasmon; single-molecule; charge-transfer; surface-enhanced Raman scattering