BITS Faculty Publications
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Item Polar Solvation Dynamics of H2O and D2O at the Surface of Zirconia Nanoparticles(ACS, 1999-08) Pant, Debi D.Time-resolved fluorescence-upconversion spectroscopy has been used to study the polar solvation dynamics of H2O and D2O at the surface of zirconia (ZrO2) nanoparticles. While an isotope effect is observed for the solvation dynamics of bulk D2O, there is no isotope effect on the interfacial solvation 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 for the interfacial dynamics is explained in terms of the solvent interacting with the ZrO2 surface.Item Polar Solvation Dynamics of H2O and D2O at the Surface of Zirconia Nanoparticles(ACS, 1999) Pant, Debi D.Time-resolved fluorescence-upconversion spectroscopy has been used to study the polar solvation dynamics of H2O and D2O at the surface of zirconia (ZrO2) nanoparticles. While an isotope effect is observed for the solvation dynamics of bulk D2O, there is no isotope effect on the interfacial solvation 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 for the interfacial dynamics is explained in terms of the solvent interacting with the ZrO2 surface.Item Experimental and Quantum Chemical Calculations of Imidazolium Appended Naphthalene Hybrid in Different Biomimicking Aqueous Interfaces(ACS, 2016) Sakhuja, Rajeev; Pant, Debi D.The effect of solvent polarity and micellar headgroup on a newly designed imidazolium based ionic liquid (IL) conjugated with naphthalene, 1,2-dimethyl-3-((6-(octyloxy)naphthalen-2-yl)methyl)-1H-imidazol-3-ium chloride (IN-O8-Cl), was studied using steady state and time-resolved fluorescence techniques. We observed that the dipole moment in the excited state is remarkably higher than the ground state. The effect of micellar surface charge on the photophysics of IN-O8-Cl in aqueous phase at room temperature was investigated. Formation of premicellar aggregates in sodium dodecylsulfate (SDS) was perceived; further the microenvironment of IN-O8-Cl was examined using steady-state fluorescence spectroscopy. Micropolarity of the micellar environment of SDS was found to be lower than that of cetyltrimethylammonium bromide (CTAB) and triton X-100 (TX100) following the order SDS < TX-100 < CTAB. The binding constant (Kb) and edge excitation red shift (EERS) from the emission maximum suggest that the probe binds strongly to the micelles. Multiexponential behavior was observed in time-resolved fluorescence lifetime studies in all micellar environments. We have observed an increase in rotational correlation time as we move from pure aqueous phase to solution containing surfactants of different head charge. Varieties of spectral parameters were used to justify the region in which the probe is present. The experimentally obtained dipole moment data were justified and explained by the DFT calculations of the electronic properties of IN-O8-Cl molecules in gas phase and in selected solvents.