München 2004 – wissenschaftliches Programm

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MO: Molekülphysik

MO 10: Femtosekundenspektroskopie: Schwingungsdynamik

MO 10.3: Vortrag

Montag, 22. März 2004, 17:00–17:15, HS 315

Vibrational multi-level quantum coherences due to anharmonic couplings in intermolecular hydrogen bonds — •Nils Huse, Karsten Heyne, Jens Dreyer, Erik T.J Nibbering, and Thomas Elsässer — Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Str. 2a, D-12489 Berlin

Femtosecond 3-pulse photon echo studies of acetic acid dimers in solution reveal multi-level coherences of O-H stretching excitations caused by the anharmonic coupling between the high-frequency stretching and low-frequency hydrogen bond motions. We demonstrate for the first time that such multi-level coherences determine the nonexponential decay of the macroscopic O-H stretching polarization, whereas spectral diffusion processes play a minor role as echo peak shift measurements and dynamic hole burning show [1,2]. The dephasing time of individual vibrational transitions contributing to the overall polarization is approximately 200 fs, much longer than the apparent rapid polarization decay.

[1] N. Huse, K. Heyne, J. Dreyer, E.T.J. Nibbering, Th. Elsaesser, Phys. Rev. Lett. (91), 197401 (2003)

[2] K. Heyne, N. Huse, J. Dreyer, E.T.J. Nibbering, Th. Elsaesser, Chem. Phys. Lett. (369), 591 (2003)