Effect of Strongly Coupled Vibration–Cavity Polaritons on the Bulk Vibrational States within a Wavelength-Scale Cavity

A Rabi splitting of 43.0 ± 1.0 cm–1 (95% conf.) was determined for the interaction of the CD3 deformation, the strongest fundamental vibration of the liquid CD3CN molecule and fringe modes of a parallel-plate Fabry–Pérot cavity containing this liquid. Note that vibration–cavity polaritons are also called dressed states, hybrid or mixed states. Since the experimental configuration has many orders of magnitude more vibrational oscillators than photons, vibrational oscillators not in dressed states far outnumber those in the dressed states. This work is distinguished from related vibration–cavity work by a method to extract the position, width, phase, and intensity of bulk vibrational signals including reconstruction of the position of the fringe without vibrational contributions. It reveals how the bulk vibrational oscillators are changed by interaction within the cavity even though they are not in dressed states. Although the dressed states are obvious targets for manipulation of chemical response, it is interesting to consider whether the lesser but more prevalent changes of the bulk vibrations can also be used to change the chemical response.