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2D THz-THz-Raman Photon-Echo Spectroscopy of Molecular Vibrations in Liquid Bromoform
Ian A Finneran1, Ralph Welsch1, Marco A Allodi1
1Division of Chemistry & Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States.
Abstract:
Fundamental properties of molecular liquids are governed by long-range interactions that most prominently manifest at terahertz (THz) frequencies. Here we report the detection of nonlinear THz photon-echo (rephasing) signals in liquid bromoform using THz-THz-Raman spectroscopy. Together, the many observed signatures span frequencies from 0.5 to 8.5 THz and result from couplings between thermally populated ladders of vibrational states. The strongest peaks in the spectrum are found to be multiquantum dipole and 1-quantum polarizability transitions and may arise from nonlinearities in the intramolecular dipole moment surface driven by intermolecular interactions.
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