Thermodynamic coupling of reactions via few-molecule vibrational polaritons

TL;DR

This paper introduces a novel cavity optomechanics approach to achieve few-molecule vibrational strong coupling, enabling thermodynamic coupling of reactions and facilitating energy transfer between otherwise non-spontaneous processes.

Contribution

It proposes an alternative method to realize single-molecule VSC using cavity-enhanced Raman spectroscopy, overcoming fabrication constraints and enabling reaction coupling.

Findings

Few-molecule vibrational polaritons can thermodynamically couple reactions.

Spontaneous electron transfer can fuel uphill reactions within the cavity.

The approach circumvents traditional cavity size limitations.

Abstract

Interaction between light and molecular vibrations leads to hybrid light-matter states called vibrational polaritons. Even though many intriguing phenomena have been predicted for single-molecule vibrational strong coupling (VSC), several studies suggest that these effects tend to be diminished in the many-molecule regime due to the presence of dark states. Achieving single or few-molecule vibrational polaritons has been constrained by the need for fabricating extremely small mode volume infrared cavities. In this work, we propose an alternative strategy to achieve single-molecule VSC in a cavity-enhanced Raman spectroscopy (CERS) setup, based on the physics of cavity optomechanics. We then present a scheme harnessing few-molecule VSC to thermodynamically couple two reactions, such that a spontaneous electron transfer can now fuel a thermodynamically uphill reaction that was non-spontaneous outside the cavity.