Physical Chemistry Seminar: Infrared Spectroscopy of vibrational polaritons

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Abstract:

Strong coupling between a privileged photonic mode and molecular excitations is typically realized by placing molecules inside resonant Fabry-Perot cavities. Recently, alternative resonator designs were developed, including arrays of scatterers, which feature high-quality surface-lattice modes. We extended this idea from visible spectral region into the mid-infrared, where arrays of half-wavelength antennas give rise to high-Q Antenna-Lattice Resonances, which strongly couple to molecular vibrations. Unlike strongly-coupled systems based on FP cavities, which reflect all incoming light except at the polariton transition frequencies, the ALR-based systems are generally transparent, whereas the incoming light is extinct at the polariton frequencies. This feature makes the ALR-based systems especially useful for studies of molecular dynamics: here, molecular degrees of freedom of interest can be directly accessed by spectroscopy, while the strong coupling is maintained.

We used the ALR-based cavities to investigate transitions of the strongly-coupled molecular vibrations in polymer films and in solutions by linear and third-order non-linear two-dimensional infrared spectroscopy (2DIR) and I will present our recent results.

Seminar Organizer: Prof. Ilia Kaminker