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

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 be largely solved by confining the liquid in an optical cavity under vibrational strong coupling conditions. For a liquid solution of 13 CO 2 solute in a 12 CO 2 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, all while the solvent is 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-Pérot cavities.

Cavity-Altered Thermal Isomerization Rates and Dynamical Resonant Localization in Vibro-Polaritonic Chemistry

“…R as defined in Eq. (21). Further, in the double-harmonic approximation, the molecular dipole function, d(Q), is expanded up to first order around Q 0 as…”

“…Several theoretical efforts have been made to explain the reactivity of molecules in cavities [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] (and related effects) under VSC. A cavity Born-Oppenheimer (cBO) approximation has been formulated in which the molecular electronic degrees of freedom separate from the nuclear and cavity degrees of freedom, and the concept of potential energy surface (PES) was extended to molecular cavity quantum electrodynamics (QED) [6][7][8] .…”

Polariton relaxation under vibrational strong coupling: Comparing cavity molecular dynamics simulations against Fermi's golden rule rate

“…We note that recent considerations of the role of VSC played by symmetry and selection rules can in princi- Selectively exciting solute molecules via solvent polariton pumping 54 . (e) Dark-mode relaxation and energy transfer dynamics 53 .…”

“…Our approach for studying polariton relaxation is classical cavity molecular dynamics (CavMD) simulations 45,[52][53][54] , in which both the cavity modes and molecular vibrations are treated classically and move along an electronic ground state surface. Compared with standard theories for strong light-matter interactions, CavMD has two advantages: the ability to (i) describe realistic molecules and (ii) treat a very large number of molecules coupled to the cavity with an affordable computational cost.…”

“…(d) Selectively exciting solute molecules via solvent polariton pumping 54 . Given the validity of the polariton enhanced molecular nonlinear absorption mechanism, CavMD shows that, if the LP of the solvent molecules can support the nonlinear transition of the solute (not the solvent) molecules only (i.e., twice the solvent LP roughly matches the solute 0 → 2 vibrational transition), pumping the solvent LP may highly excite the solute molecules, leaving the solvent molecules barely excited.…”