The origin of ultrafast proton transfer: multidimensional wave packet motion vs. tunneling
Chem. Phys. Lett., 2011, 503, 61-65 published on 08.02.2011
Chem. Phys. Lett.
We investigate the reaction kinetics of ultrafast excited state intramolecular proton transfer (ESIPT) and discuss the possible origins of the process: Tunneling of the reactive proton, vibrationally enhanced tunneling, and multidimensional wave packet dynamics of the entire system. Comparison of the measured kinetics for the protonated and the deuterated form of 2-(2'-hydroxyphenyl)benzothiazole (HBT) to numerical simulations allows us to ascribe the characteristic 50 fs time found for the ESIPT solely to a ballistic wave packet motion along skeletal coordinates that mainly affect the donor acceptor distance. Tunneling is not found to be decisive.