Speaker
Description
Understanding spectroscopic signatures of polaritonic systems is essential for probing processes in polariton-controlled chemistry and photovoltaic devices. Transient absorption spectroscopy enables the study of energy transfer pathways between polaritons and dark states, as well as between dark states, which evolve on picosecond (ps) timescales, in contrast to the femtosecond (fs) decay of polaritons. We combine transient absorption measurements with theoretical modeling to investigate energy transfer from rhodamine 3B (λmax = 561 nm) to oxazine-1 (λmax = 653 nm) in a Fabry-Perot microcavity under strong coupling. By tuning cavity detuning and donor-acceptor ratios, we observe both enhancement and suppression of transfer rates. Using Redfield theory with a microscopic multi-mode Tavis-Cummings Hamiltonian, we show that transfer is enhanced when the cavity is resonant with acceptors, but suppressed when resonant with donors. This behavior arises from the degree of polariton-acceptor hybridization, which governs the efficiency of energy flow. Our results highlight cavity detuning as a key control parameter for engineering energy transfer in polaritonic systems.