Browsing by Author "Nibbering, E.T.J."

Now showing 1 - 4 of 4
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    Competition between excited state proton and OH- transport via a short water wire: Solvent effects open the gate
    (London [u.a.] : Royal Society of Chemistry, 2014) Bekçioǧlu, G.; Allolio, C.; Ekimova, M.; Nibbering, E.T.J.; Sebastiani, D.
    We investigate the acid-base proton exchange reaction in a microsolvated bifunctional chromophore by means of quantum chemical calculations. The UV/vis spectroscopy shows that equilibrium of the keto-and enol-forms in the electronic ground state is shifted to the keto conformation in the excited state. A previously unknown mechanism involving a hydroxide ion transport along a short water wire is characterized energetically, which turns out to be competitive with the commonly assumed proton transport. Both mechanisms are shown to have a concerted character, as opposed to a step-wise mechanism. The alternative mechanism of a hydrogen atom transport is critically examined, and evidence for strong solvent dependence is presented. Specifically, we observe electrostatic destabilization of the corresponding πσ* state by the aqueous solvent. As a consequence, no conical intersections are found along the reaction pathway.
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    Ultrafast IR pump-probe and 2D-IR photon echo spectroscopy of adenosine-thymidine base pairs
    (Les Ulis : EDP Sciences, 2013) Greve, C.; Preketes, N.K.; Costard, R.; Koeppe, B.; Fidder, H.; Nibbering, E.T.J.; Temps, F.; Mukamel, S.; Elsaesser, T.
    We characterize diagonal and off-diagonal anharmonicities of N-H stretching vibrations in adenosine and thymidine monomers and in A•T-base pairs in chloroform solution, showing the important role of coupling between vibrationally excited N-H stretching states.
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    Ultrafast OH-stretching frequency shifts of hydrogen-bonded 2-naphthol photoacid-base complexes in solution
    (Les Ulis : EDP Sciences, 2013) Prémont-Schwarz, M.; Xiao, D.; Sekharan, S.; Batista, V.S.; Nibbering, E.T.J.
    We characterize the transient solvent-dependent OH-stretching frequency shifts of photoacid 2-naphthol hydrogen-bonded with CH3CN in the S0- and S1-states using a combined experimental and theoretical approach, and disentangle specific hydrogen-bonding contributions from nonspecific dielectric response.
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    Ultrafast proton coupled electron transfer (PCET) dynamics in 9-anthranol-aliphatic amine system
    (Les Ulis : EDP Sciences, 2013) Ghosh, H.N.; Adamczyk, K.; Verma, S.; Dreyer, J.; Nibbering, E.T.J.
    Femtosecond infrared absorption studies strongly suggest that photoexcited 9-anthranol takes part in an ultrafast electron transfer (ET) reaction in electron-donating triethylamine solvent, but that ultrafast proton coupled electron transfer (PCET) occurs in diethylamine solvent.