Differential Wavevector Distribution of Surface-Enhanced Raman Scattering and Fluorescence in a Film-Coupled Plasmonic Nanowire Cavity
- Indian Inst. of Science Education and Research (IISER), Pune (India). Photonics and Optical Nanoscopy Lab. and Dept. of Physics
- Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials
- Indian Inst. of Science Education and Research (IISER), Pune (India). Center for Energy Science, Photonics and Optical Nanoscopy Lab. and Dept. of Physics
Here, we report on the experimental observation of differential wavevector distribution of surface-enhanced Raman scattering (SERS) and fluorescence from dye molecules confined to a gap between plasmonic silver nanowire and a thin, gold mirror. The fluorescence was mainly confined to higher values of in-plane wavevectors, whereas SERS signal was uniformly distributed along all the wavevectors. The optical energy momentum spectra from the distal end of the nanowire revealed strong polarization dependence of this differentiation. All these observations were corroborated by full-wave three-dimensional numerical simulations, which further revealed an interesting connection between out-coupled wavevectors and parameters such as hybridized modes in the gap-plasmon cavity, and orientation and location of molecular dipoles in the geometry. Our results reveal a new prospect of discriminating electronic and vibrational transitions in resonant dye molecules using a subwavelength gap plasmonic cavity in the continuous-wave excitation limit, and can be further harnessed to engineer molecular radiative relaxation processes in momentum space.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division; Dept. of Science and Technology (India); Indo-U.S. Science and Technology Forum (IUSSTF)
- Grant/Contract Number:
- AC02-06CH11357; SR/NM/NS-1141/2012; SR/NM/TP-13/2016
- OSTI ID:
- 1461299
- Journal Information:
- Nano Letters, Vol. 18, Issue 1; ISSN 1530-6984
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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