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Start date: 1990 × End date: 1999 × Publisher: Routledge : Taylor and Francis Inc. ×

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Now showing 1 - 3 of 3
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    Resonance Raman and optical dephasing study of HITCI
    (Routledge : Taylor and Francis Inc., 1999) Kummrow, A.; Ashworth, S.H.; Lenz, K.
    Line shape analysis based on resonance Raman spectra of HITCI is used to determine the details of the vibrational part of the line broadening function. Forced Light Scattering with 20 fs pulses from a Ti: sapphire laser measured optical dephasing probing with an Ar+ laser. The observed response is well described by the line broadening function derived from the fluorescence line shape.
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    Molecular dynamics investigated by temporally two-dimensional coherent Raman spectroscopy
    (Routledge : Taylor and Francis Inc., 1999) Lau, A.; Pfeiffer, M.; Kozich, V.; Kummrow, A.
    A six-wave set-up is described to determine molecular dynamics in the condensed phase. Applying two independent time delays between excitation and probe pulses additional information on the dynamics should be obtainable. We show experimentally that such investigations can be carried out with noisy light having intensity fluctuations in the femtosecond region. As first result we found a fast relaxation time in neat nitrobenzene of 100 fs, becoming even faster in mixtures with low viscosity liquids. Switching on a Raman resonance yields a longer relaxation time, which could be explained by an additional contribution by that vibration.
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    Coherent motion of low frequency vibrations in ultrafast excited state proton transfer
    (Routledge : Taylor and Francis Inc., 1999) Pfeiffer, M.; Chudoba, C.; Lau, A.; Lenz, K.; Elsaesser, T.
    Photoexcitation of internal proton transfer in the tinuvin molecule causes the excitation of some low frequency vibrational modes which oscillate with high amplitudes in a coherent manner over 700 fs. Such effect is observed for the first time applying two color pump/probe measurement with 25 fs pulses. Based on resonance Raman spectra a normal coordinate analysis of the modes is performed. It is shown that the nuclear movement given by the normal vibration of one of the modes serves to open up a barrierfree proton transfer path.