Influence of Vibrational Strong Coupling on an Ordered Liquid Crystal.

Vibrational strong coupling and the formation of vibrational polaritons are a result of strong light-matter interaction between a cavity photon and a molecular vibrational mode. The Rabi splitting parameter, which reflects the microscopic light-matter interaction strength, reveals information about the molecular alignment and concerted vibrational motion inside the cavity. We have investigated vibrational strong coupling of 4-cyano-4'-octylbiphenyl liquid crystal molecules in isotropic and smectic A phases.

Development of a Spacerless Flow-Cell Cavity for Vibrational Polaritons.

We developed a spacerless flow-cell cavity for the observation of vibrational strong coupling and demonstrate its availability in two samples with a C≡N bond: a metal complex (aq) and an ionic liquid. It is shown that the cavity length can be tuned over a wide range to investigate coupling with different order Fabry-Pérot cavity modes without reassembling the cavity. In the ionic liquid, analyses based on the coupled harmonic oscillator model with multiple vibrational modes show that the Rabi splitting parameters and the square root of the integrated absorption intensity are proportional among the three neighboring vibrational modes.