CC BY 3.0 UnportedPfeiffer, M.Chudoba, C.Lau, A.Lenz, K.Elsaesser, T.2020-08-072020-08-071999https://doi.org/10.34657/4033https://oa.tib.eu/renate/handle/123456789/5404Photoexcitation 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.enghttps://creativecommons.org/licenses/by/3.0/530Excited state-moleculesPotential energy surfaceProton transferRaman spectra-moleculesUltrafast time resolved spectraArticle