Cavity molecular dynamics simulations of vibrational polariton-enhanced molecular nonlinear absorption

Journal Article · Fri Mar 05 04:00:00 EST 2021 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/5.0037623· OSTI ID:1853204

Li, Tao E. ^[1]; Nitzan, Abraham ^[2]; Subotnik, Joseph E. ^[3]

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1. University of Pennsylvania, Philadelphia, PA (United States); Univ. of Pennsylvania, Philadelphia, PA (United States)
2. University of Pennsylvania, Philadelphia, PA (United States); Tel Aviv University, Tel Aviv (Israel)
3. University of Pennsylvania, Philadelphia, PA (United States)

We report recent experiments have observed that the chemical and photophysical properties of molecules can be modified inside an optical Fabry– Pérot microcavity under collective vibrational strong coupling (VSC) conditions, and such modification is currently not well understood by theory. In an effort to understand the origin of such cavity-induced phenomena, some recent studies have focused on the effect of the cavity environment on the nonlinear optical response of the molecular subsystem. Here, we use a recently proposed protocol for classical cavity molecular dynamics simulations to numerically investigate the linear and the nonlinear response of liquid carbon dioxide under such VSC conditions following an optical pulse excitation. We find that applying a strong pulse of excitation to the lower hybrid light–matter state, i.e., the lower polariton (LP), can lead to an overall molecular nonlinear absorption that is enhanced by up to two orders of magnitude relative to the excitation outside the cavity. This polariton-enhanced multiphoton absorption also causes an ultrashort LP lifetime (0.2 ps) under strong illumination. Unlike usual polariton relaxation processes—whereby polaritonic energy transfers directly to the manifold of singly excited vibrational dark states—under the present mechanism, the LP transfers energy directly to the manifold of higher vibrationally excited dark states; these highly excited dark states subsequently relax to the manifold of singly excited states with a lifetime of tens of ps. Because the present mechanism is generic in nature, we expect these numerical predictions to be experimentally observed in different molecular systems and in cavities with different volumes.

• Research Organization: Univ. of Pennsylvania, Philadelphia, PA (United States); Univ. of California, Oakland, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division
• Grant/Contract Number: SC0019397; AC02-05CH11231
• OSTI ID: 1853204
• Alternate ID(s): OSTI ID: 1769422
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 9 Vol. 154; ISSN 0021-9606
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
equilibrium thermodynamics
molecular dynamics
multiphoton processes
nonlinear optics
optical nonlinearities
optical resonators
strong interactions
vibrational states