期刊
ACS NANO
卷 13, 期 7, 页码 7644-7654出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.9b00776
关键词
nonlocal screening; charge spill-out; surface-enhanced Raman spectroscopy; nanoparticle-on-film nanocavities; graphene
类别
资金
- National Natural Science Foundation of China [11474240]
- Research Grant Council of Hong Kong [PolyU 15305718]
- Hong Kong Polytechnic University [1-ZE6G]
When the geometric features of plasmonic nanostructures approach the subnanometric regime, non local screening and charge spill-out of metallic electrons will strongly modify the optical responses of the structures. While quantum tunneling resulting from charge spill-out has been widely discussed in the literature, the near-field enhancement saturation caused by the nonlocal screening effect still lacks a direct experimental verification. In this work, we use surface-enhanced Raman spectroscopy (SERS) of graphene to probe the in-plane near-field enhancement limit in gold nanosphere-on-film nanocavities where different layers of graphene are sandwiched between a gold nanosphere and a gold film. Together with advanced transmission electron microscopy cross-sectional imaging and nonlocal hydrodynamic theoretical calculations, the cavity gap width correlated SERS and dark-field scattering measurements reveal that the intrinsic nonlocal dielectric response of gold limits the near-field enhancement factors and mitigates the plasmon resonance red-shift with decreasing the gap width to less than one nanometer. Our results not only verify previous theoretical predictions in both the near-field and far-field regime but also demonstrate the feasibility of controlling the near- and far-field optical response in such versatile plasmonic particle-graphene-on-film nanocavities, which can find great potential in applications of graphene-based photonic devices in the visible and near-infrared region.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据