Anna Uritski

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A time-resolved emission technique was employed to study the photoprotolytic cycle of two photoacids 2-naphtol-6-sulfonate (2N6S) and 2-naphtol-6,8-disulfonate (2N68DS) in ice in the presence of a low concentration of a weak base fluoride ion. We found that an additional proton-transfer process occurs in ice doped with F- ions. This reaction takes place(More)
We have studied the excited-state proton-transfer rate of four photoacids in ice as a function of temperature. For all four photoacids, we have found a non Arrhenius behavior of the proton-transfer rate constant, k(PT). d(ln k(PT))/d(1/T) decreases as the temperature decreases. The average slope of ln(k(PT))versus 1/T depends on the photoacid strength(More)
The effects of excess protons on the fluorescence quenching process of 1-naphthol-4-sulfonate (1N4S) and 1-naphthol-3-sulfonate (1N3S) in methanol-doped ice samples were studied by employing a time-resolved emission technique. We found that the fluorescence quenching of the deprotonated form RO(-)* of both photoacids by protonation is very efficient in ice,(More)
Steady-state and time-resolved emission techniques were employed to study the photoprotolytic cycle of an excited photoacid in ice in the presence of a low concentration of a weak base-like F(-). In previous studies we found that the photoprotolytic cycle in methanol-doped ice (1% mol fraction) is too slow to be observed at temperatures below 190 K. In this(More)
Time-resolved emission was used to measure the photoprotolytic cycle of an excited photoacid as a function of temperature, both in liquid water and in ice, in the presence of an inert salt. The inert salt affects the geminate recombination between the transferred proton with the conjugate base of the photoacid. We used the Debye-Hückel theory to express the(More)
The reversible proton dissociation and geminate recombination of a photoacid is studied as a function of temperature in water electrolyte solutions and binary water-methanol mixtures, containing 0.1 and 0.2 mole fractions of methanol. 8-Hydroxypyrene-1,3,6-trisulfonate trisodium salt (HPTS) is used as the photoacid. The experimental data are analyzed by the(More)
We have studied the solvation statics and dynamics of coumarin 343 and a strong photoacid (pK* approximately 0.7) 2-naphthol-6, 8-disulfonate (2N68DS) in methanol-doped ice (1% molar concentration of methanol) and in cold liquid ethanol in the temperature range of 160-270 K. Both probe molecules show a relatively fast solvation dynamics in ice, ranging from(More)
Time-resolved emission and steady-state fluorescence techniques are used to study the excited-state intermolecular proton transfer from 8-hydroxypyrene-1,3,6-trisulfonate (HPTS or pyranine) to water in the presence of inert salts, NaCl and MgCl(2). At low salt concentrations, up to about 0.5 M MgCl(2) or about 0.8 M NaCl, the time-resolved emission of both(More)
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