Event Details

Optics News

Highlights From FiO 2018

Speaker: Mariia Shutova

Mariia is going to present several topics from Frontiers in Optics conference and highlight the main trends driving the field of optics and laser physics.

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Main Talk

Two-Dimensional Spectroscopy for Vibrational Molecular Polaritons

Speaker: Zhedong Zhang

Recently the technical advances made researchers able to perform two-dimensional spectroscopy in various regimes, i.e., visible and infrared (IR), and correlate transition frequencies that evolve in different time intervals, although pico- and femto-second time-resolved spectroscopies of electronic transitions have come of age [1]. 2DES correlates excitation and emission energies as a function of a delay time between excitation and emission/transient-excitation events, within the bandwidth of the laser pulse [2,3]. 2D spectra are plotted as a function of absorption and emission, and cross-peaks appear where the two frequencies are different, indicating many-body interactions and excited-state relaxation. Here I will explain our recent work on 2DIR spectroscopy for resolving the cooperative properties of molecules strongly coupled with quantized photons, where the local fluctuations, i.e., disorder, are essentially incorporated. The results reveal the dark states by the cross peaks apart from the ones from polariton modes, as a result of the breakdown of cooperativity between molecules. We further show that the breakdown of cooperativity profoundly connects to the localization of the vibrational excitations whereas the polariton modes are extended wave over several molecules. Our work offers new physical insight for understanding the recent 2D-IR experiments [4]. Finally I will briefly talk about the resonant Raman spectra from the point of view of 2D spectroscopy.

References

- Lomsadze and Cundiff, Phys. Rev. Lett. 120, 233401 (2018)
- Mukamel, Annu. Rev. Phys. Chem. 51, 691 (2000)
- Cho, Chem. Rev. 108, 1331 (2008)
- Xiang, et al., PNAS 115, 4845 (2018)