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-Pe??rot 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. Our spacerless cell structure simplifies the comparison of the different vibrational strong coupling measurements, such as the mode order dependence and the coupling to different molecular vibrations.

Automated summary

We developed a spacerless flow-cell cavity for the observation of vibrational strong coupling and demonstrated its availability in two samples with a C???N bond: a metal complex (aq) and an ionic liquid. The cavity length can be tuned to investigate coupling with different order Fabry-Pe??rot cavity modes without reassembling the cavity. In the ionic liquid, analysis showed that the Rabi splitting parameters and the square root of the integrated absorption intensity are proportional among the three neighboring vibrational modes. The spacerless cell structure simplifies the comparison of different vibrational strong coupling measurements.