TY - JOUR
T1 - Excited-state proton transfer and proton diffusion near hydrophilic surfaces
AU - Soroka, Hagit Peretz
AU - Simkovitch, Ron
AU - Kosloff, Alon
AU - Shomer, Shay
AU - Pevzner, Alexander
AU - Tzang, Omer
AU - Tirosh, Reuven
AU - Patolsky, Fernando
AU - Huppert, Dan
PY - 2013/12/5
Y1 - 2013/12/5
N2 - Time-resolved emission techniques were employed to study the reversible proton photoprotolytic properties of surface-attached 8-hydroxypyrene-1,3,6- trisulfonate (HPTS) molecules to hydrophilic alumina and silica surfaces. We found that the excited-state proton transfer rate of the surface-linked HPTS molecules, in H2O and D2O, is nearly the same as of HPTS in the bulk, while the corresponding recombination rate is significantly greater. Using the diffusion-assisted proton geminate-recombination model, we found that the best fit of the time-resolved fluorescence (TRF) signal is obtained by invoking a two-dimensional diffusion space for the proton to recombine with the conjugated basic form, RO-*, of the surface-linked HPTS. However, we obtain an excellent fit by a three-dimensional diffusion space for diffusional HPTS in bulk water. These results indicate that the photoejected solvated protons are confined to the surface for long periods of time. We suggest two plausible mechanisms responsible for two-dimensional proton diffusion next to hydrophilic surfaces.
AB - Time-resolved emission techniques were employed to study the reversible proton photoprotolytic properties of surface-attached 8-hydroxypyrene-1,3,6- trisulfonate (HPTS) molecules to hydrophilic alumina and silica surfaces. We found that the excited-state proton transfer rate of the surface-linked HPTS molecules, in H2O and D2O, is nearly the same as of HPTS in the bulk, while the corresponding recombination rate is significantly greater. Using the diffusion-assisted proton geminate-recombination model, we found that the best fit of the time-resolved fluorescence (TRF) signal is obtained by invoking a two-dimensional diffusion space for the proton to recombine with the conjugated basic form, RO-*, of the surface-linked HPTS. However, we obtain an excellent fit by a three-dimensional diffusion space for diffusional HPTS in bulk water. These results indicate that the photoejected solvated protons are confined to the surface for long periods of time. We suggest two plausible mechanisms responsible for two-dimensional proton diffusion next to hydrophilic surfaces.
UR - http://www.scopus.com/inward/record.url?scp=84890343918&partnerID=8YFLogxK
U2 - 10.1021/jp4087514
DO - 10.1021/jp4087514
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AN - SCOPUS:84890343918
SN - 1932-7447
VL - 117
SP - 25786
EP - 25797
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 48
ER -