Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany.
Nano Lett. 2013 Jan 9;13(1):301-8. doi: 10.1021/nl3041542. Epub 2012 Dec 11.
We characterize plasmonic enhancement in a hotspot between two Au nanodisks using Raman scattering of graphene. Single layer graphene is suspended across the dimer cavity and provides an ideal two-dimensional test material for the local near-field distribution. We detect a Raman enhancement of the order of 10(3) originating from the cavity. Spatially resolved Raman measurements reveal a near-field localization one order of magnitude smaller than the wavelength of the excitation, which can be turned off by rotating the polarization of the excitation. The suspended graphene is under tensile strain. The resulting phonon mode softening allows for a clear identification of the enhanced signal compared to unperturbed graphene.
我们利用石墨烯的喇曼散射来描述两个 Au 纳米盘之间热点处的等离子体增强。单层石墨烯悬于二聚体腔的上方，为局部近场分布提供了理想的二维测试材料。我们检测到源自腔的约 10(3)数量级的喇曼增强。空间分辨的喇曼测量揭示了近场局域化程度比激发波长小一个数量级，这可以通过旋转激发的偏振来关闭。悬空的石墨烯受到拉伸应变。与未受扰的石墨烯相比，由此产生的声子模式软化允许对增强信号进行清晰的识别。
