Signatures of Vibrational Strong Coupling in Raman Scattering

TL;DR

This paper theoretically investigates how vibrational strong coupling with cavity modes influences Raman scattering, revealing that while the total Raman signal remains constant, its distribution shifts between polaritons, explaining experimental enhancements.

Contribution

It provides a theoretical analysis showing the redistribution of Raman signals under vibrational strong coupling, aligning with recent experimental observations.

Findings

Total Raman cross section remains constant across coupling regimes.

Raman signal redistributes between polaritons in strong coupling.

Experimental Raman enhancements are explained by signal redistribution.

Abstract

In this Letter we analyze theoretically how the emergence of collective strong coupling between vibrational excitations and confined cavity modes affects Raman scattering processes. This work is motivated by recent experiments [Shalabney et al., Angew. Chemie 54, 7971 (2015)], which reported enhancements of up to three orders of magnitude in the Raman signal. By using different models within linear response theory, we show that the total Raman cross section is maintained constant when the system evolves from the weak-coupling limit to the strong-coupling regime. A redistribution of the Raman signal among the two polaritons is the main fingerprint of vibrational strong coupling in the Raman spectrum.