Mid-infrared-perturbed molecular vibrational signatures in plasmonic nanocavities  

作　　者：Rohit Chikkaraddy Angelos Xomalis Lukas A.Jakob Jeremy J.Baumberg 

机构地区：[1]NanoPhotonics Centre,Cavendish Laboratory,Department of Physics,JJ Thompson Avenue,University of Cambridge,Cambridge CB30HE,UK [2]Empa,Swiss Federal Laboratories for Materials Science and Technology,Laboratory for Mechanics of Materials and Nanostructures,Thun,Switzerland

出　　处：《Light(Science & Applications)》2022年第1期127-135,共9页光（科学与应用)（英文版）

基　　金：The authors acknowledge support from European Research Council(ERC)under Horizon 2020 research and innovation programme PICOFORCE(Grant Agreement No.861950);THOR(Grant Agreement No.829067);POSEIDON(Grant Agreement No.861950);the EPSRC(Cambridge NanoDTC EP/L015978/1,EP/L027151/1,EP/S022953/1,EP/P029426/1,and EP/R020965/1);R.C.acknowledges support from Trinity College,University of Cambridge.

摘　　要：Recent developments in surface-enhanced Raman scattering(SERS)enable observation of single-bond vibrations in real time at room temperature.By contrast,mid-infrared(MIR)vibrational spectroscopy is limited to inefficient slow detection.Here we develop a new method for MIR sensing using SERS.This method utilizes nanoparticle-on-foil(NPoF)nanocavities supporting both visible and MIR plasmonic hotspots in the same nanogap formed by a monolayer of molecules.Molecular SERS signals from individual NPoF nanocavities are modulated in the presence of MIR photons.The strength of this modulation depends on the MIR wavelength,and is maximized at the 6–12μm absorption bands of SiO_(2) or polystyrene placed under the foil.Using a single-photon lock-in detection scheme we time-resolve the rise and decay of the signal in a few 100 ns.Our observations reveal that the phonon resonances of SiO_(2) can trap intense MIR surface plasmons within the Reststrahlen band,tuning the visible-wavelength localized plasmons by reversibly perturbing the localized few-nm-thick water shell trapped in the nanostructure crevices.This suggests new ways to couple nanoscale bond vibrations for optomechanics,with potential to push detection limits down to single-photon and single-molecule regimes.

关 键 词：visible SIGNATURE utilize 

分 类 号：O53[理学—等离子体物理]