Optomechanical Effects in Nanocavity-enhanced Resonant Raman Scattering of a Single Molecule

TL;DR

This paper develops a quantum master equation theory to study optomechanical effects in single-molecule resonant Raman scattering within nanocavities, revealing phenomena like vibrational pumping, Mollow triplets, and higher-order scattering.

Contribution

It introduces a novel theoretical framework combining quantum electrodynamics and electron-vibration interactions for single-molecule SERRS in nanocavities.

Findings

Identification of conditions for vibrational pumping and non-linear scattering

Discovery of Mollow triplet side-bands in Raman spectra

Observation of higher-order Raman scattering phenomena

Abstract

In this article, we address the optomechanical effects in surface-enhanced resonant Raman scattering (SERRS) from a single molecule in a nano-particle on mirror (NPoM) nanocavity by developing a quantum master equation theory, which combines macroscopic quantum electrodynamics and electron-vibration interaction within the framework of open quantum system theory. We supplement the theory with electromagnetic simulations and time-dependent density functional theory calculations in order to study the SERRS of a methylene blue molecule in a realistic NPoM nanocavity. The simulations allow us not only to identify the conditions to achieve conventional optomechanical effects, such as vibrational pumping, non-linear scaling of Stokes and anti-Stokes scattering, but also to discovery distinct behaviors, such as the saturation of exciton population, the emergence of Mollow triplet side-bands, and higher-order Raman scattering. All in all, our study might guide further investigations of optomechanical effects in resonant Raman scattering.