Effect of molecular Stokes shift on polariton dynamics

Area of Science:

• • Cavity quantum electrodynamics
• • Light-matter interactions
• • Molecular spectroscopy

Background:

• • Strong coupling between light and matter forms hybrid states called polaritons.
• • Polaritons offer potential for controlling molecular chemistry.
• • Metallic Fabry-Pérot cavities confine light modes to interact with photoactive molecules.

Purpose of the Study:

• • To investigate the role of the molecular Stokes shift in polariton relaxation.
• • To differentiate relaxation mechanisms in organic molecules with varying Stokes shifts.
• • To elucidate energy transfer processes in light-matter coupled systems.

Main Methods:

• • Angle-resolved steady-state experiments.
• • Multi-scale molecular dynamics simulations.
• • Analysis of polariton dispersion and relaxation pathways.

Main Results:

• • Molecular Stokes shift dictates polariton relaxation pathways.
• • Rhodamine 6G (large Stokes shift) exhibits radiative pumping via the fluorescing state.
• • J-aggregates (negligible Stokes shift) use vibrationally assisted scattering for relaxation.
• • Non-adiabatic couplings drive energy transfer from uncoupled molecules to polaritons.

Conclusions:

• • The Stokes shift is a critical parameter in designing polaritonic chemistry.
• • Understanding relaxation mechanisms is key to controlling light-matter interactions.
• • Molecular dynamics simulations provide insights into energy transfer in strongly coupled systems.