Energy-efficient pathway for selectively exciting solute molecules to high vibrational states via solvent vibration-polariton pumping

TL;DR

This study demonstrates that vibrational strong coupling in optical cavities can significantly enhance the selective excitation of solute molecules to high vibrational states using solvent vibration-polariton pumping, potentially improving IR-driven chemical reactions.

Contribution

It introduces a cavity-based method to efficiently excite solute molecules to high vibrational states via solvent polariton pumping, a novel approach in vibrational chemistry.

Findings

Strong ultrafast excitation of solutes via solvent polaritons

Enhanced selectivity in vibrational excitation within cavities

Robustness of effect across different cavity volumes

Abstract

Selectively exciting target molecules to high vibrational states is inefficient in the liquid phase, which restricts the use of IR pumping to catalyze ground-state chemical reactions. Here, we demonstrate that this inefficiency can sometimes be solved by confining the liquid to an optical cavity under vibrational strong coupling conditions. For a liquid solution of 13CO2 solute in a 12CO2 solvent, cavity molecular dynamics simulations show that exciting a polariton (hybrid light-matter state) of the solvent with an intense laser pulse, under suitable resonant conditions, may lead to a very strong (> 3 quanta) and ultrafast (< 1 ps) excitation of the solute, even though the solvent ends up being barely excited. By contrast, outside a cavity the same input pulse fluence can excite the solute by only half a vibrational quantum and the selectivity of excitation is low. Our finding is robust under different cavity volumes, which may lead to observable cavity enhancement on IR photochemical reactions in Fabry-P\'erot cavities.