Time-resolved fluorescence-upconversion spectroscopy has been used to study
the polar solvation dynamics of H2O and D2O at the surface of zirconia (Zr
O2) nanoparticles. While an isotope effect is observed for the solvation dy
namics of. bulk D2O, there is no isotope effect on the interfacial solvatio
n dynamics. The interfacial solvation dynamics are the same for H2O and D2O
and are faster than the bulk solutions. The bulk isotope effect is due to
stronger hydrogen bonding in D2O compared to H2O, slowing the reorientation
of the excited-state dipoles in the bulk D2O. The lack of isotope effect f
or the interfacial dynamics is explained in terms of the solvent interactin
g with the ZrO2 surface.