Dynamics of Vibration-Cavity Polaritons; New Absorbers but the Same Interpretation

Jeffrey Owrutsky US Naval Research Laboratory

Jeffrey C. Owrutsky, (1) Blake Simpkins, (1) Andrea Grafton, (2) Cynthia Pyles (3) and Adam D. Dunkelberger (1)

(1) US Naval Research Laboratory, Washington, DC USA

(2) Former NRC RAP Postdoctoral Associate, now at Coherent

(3) ASEE Postdoctoral Associate

Strong coupling between an optical mode and an ensemble of molecular vibrations creates new vibration- cavity polariton modes, which have been shown to modify reaction dynamics and branching ratios even without excitation. Studies on the ultrafast nonlinear spectroscopy and dynamics of the polaritonic system might elucidate the mechanism of the reaction modification as well as shed light on novel applications in photonics. Most of the work to date on ultrafast molecular cavity polariton dynamics involved hexacarbonyls in solution. We will describe recent results for transient absorption studies of strong coupling to nitroprusside and thiocyanate ions, which also have strong infrared transitions but are distinct from hexacarbonyls in several important respects. We discuss the similarities and differences between the vibration-cavity polariton dynamics in these systems and how the results generally solidify our understanding of polariton dynamics. We find that most of the vibration cavity polariton response, especially at long times, can be properly reproduced based on classical etalon transmission. This approach relies on including an absorbing layer modeled with a complex dielectric function that depends on the ground and excited state populations. As a result, extracting the excited polariton response can be challenging and it seems to be quite short lived in the systems we have investigated.