Abstract
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•Graphene/Ag NPs reveal promising features for imaging/sensing in nanoscale regime.•Ag NPs beneath graphene were used as plasmonic nanoheaters excited by the probe laser.•N-doping of graphene was inferred from Raman parameters dependence on laser power.•The enhanced peak intensity/low background is favorable for sensing applications.•Power dissipation due to substrate effects are excluded in Graphene/Ag NPs device.
Raman spectra of graphene on single Ag nanoparticles (Ag NPs) reveal promising features for quantum and imaging/sensing applications in the nanoscale regime. The active Raman modes of graphene monolayer act as a Raman Thermometry and Ag NPs act as plasmonic nanoheaters excited by the probe laser. The thermal probing resolution can reach the nanometer scale determined by the graphene area attached to the Ag NPs. In addition to the Raman shift and intensity enhancement, the G-peak half width (ΓG) decreases with increasing the laser power inferring the photo-induced electron transfer from AgNPs to the attached graphene area; we are the first to report ΓG reduction by thermal investigations. The proposed graphene/Ag NPs structure is exempt from power dissipation due to substrate effects such as the thermal coupling between graphene and substrate. Graphene plasmons bound to the surface at the nanoscale size driven by the photo-induced electron transfer from single Ag NPs are promising for quantum plasmonic applications that have been difficult to be achieved with conventional metal plasmonics.