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O: Fachverband Oberflächenphysik

O 35: Poster Session III: Surface dynamics I: Phase transitions and elementary processes

O 35.2: Poster

Tuesday, March 2, 2021, 10:30–12:30, P

Time-Resolved 2D IR Pump-Probe Spectroscopy — Michael Lackner, •Marvin Hille, Tim Lämmerzahl, Nelli Kremer, and Eckart Hasselbrink — University of Duisburg-Essen, Essen, Germany

Internal vibrational energy distribution (IVR) in molecules is fundamental for understanding their chemical reactivity and research in this field has gained a lot of popularity in the past. It is, however, still fair to say that predictive power over the energy flow in vibrationally excited molecules has yet to be obtained. We will present newest findings regarding the energy flow dynamic of a fatty acid Langmuir-Blodgett film on a picosecond scale. Vibrational sum frequency generation (vSFG) spectroscopy allows precise monitoring of resonant vibrations of an adsorbate monolayer. In our setup we use a resonant ps narrowband IR laser pulse for pumping and a fs broadband IR-visible pulse pair for vSFG probing of the monolayer. Using this pump-probe setup we observed a very fast (< 2ps) energy transfer to the other modes when pumping the anti-symmetric methyl or methylene stretch, followed by a longer decay (~85 ps) into presumably bending and internal rotational modes.