Düsseldorf 2007 – scientific programme

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MO: Fachverband Molekülphysik

MO 21: Femtosecond Spectroscopy II

MO 21.2: Talk

Tuesday, March 20, 2007, 11:00–11:15, 6D

Ultrafast dynamics of vibrational N-H stretching excitations in the 7-azaindole dimer — •Jason R. Dwyer, Jens Dreyer, Erik T. J. Nibbering, and Thomas Elsaesser — Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, D-12489 Berlin, Germany

The ultrafast vibrational response of hydrogen bonds in the 7-azaindole dimer, a model compound for DNA base pairing, is studied in infrared pump-probe experiments. We observe a ~ 100 fs relaxation of the v = 1 state of the N-H stretching oscillators via anharmonically coupled over- and combination tones of fingerprint modes. In the monomer with a larger energy mismatch between the v = 1 state and over-/combination tones, a much longer lifetime of 10 ps is found. Femtosecond N-H stretching excitation induces coherent underdamped motions of the dimer, dominated by the anharmonically coupled 110 cm-1 stretching mode of the hydrogen bonds.