Femtosecond studies of electron-cation dynamics in neat water: The effects of isotope substitution

Abstract Femtosecond photoionization studies in neat protio and deuterio water at room temperature have been performed. The rate of appearance of the solvated electron is slower in D 2 O than in H 2 O, consistent with the predictions of continuum theories. The observed geminate recombination dynamics of the cation-electron pair is also isotope dependent. The recombination time is slower in D 2 O and the fraction of solvated electrons that escape recombination is greater in D 2 O than in H 2 O. After 165 ps, 54±1% (±one standard deviation) of the solvated electrons escape geminate recombination in H 2 O and 62±1% escape in D 2 O. The increased electron escape yield is attributed to an energy transfer effect on the electron thermalization distance.

[1]  K. Schmidt,et al.  Mobility of the Hydrated Electron , 1966, Science.

[2]  C. Jonah.  Decay of geminate ions in hexanes , 1983 .

[3]  R. Yen,et al.  Amplification of 70‐fs optical pulses to gigawatt powers , 1982 .

[4]  F. Jou,et al.  Temperature and isotope effects on the shape of the optical absorption spectrum of solvated electrons in water , 1979 .

[5]  U. Landman,et al.  Relaxation dynamics following transition of solvated electrons , 1989 .

[6]  L. Onsager.  Initial Recombination of Ions , 1938 .

[7]  K. Eisenthal,et al.  Femtosecond study of geminate electron–hole recombination in neat alkanes , 1988 .

[8]  Aneesur Rahman,et al.  Hydrated electron revisited via the feynman path integral route , 1986 .

[9]  C. Braun,et al.  Picosecond transient absorption measurements of geminate electron-cation recombination , 1987 .

[10]  Alexander A. Oraevsky,et al.  Two-photon ionization and dissociation of liquid water by powerful laser UV radiation , 1983 .

[11]  H. Schwarz.  Applications of the spur diffusion model to the radiation chemistry of aqueous solutions , 1969 .

[12]  P. Delahay,et al.  Photoelectron emission spectroscopy of liquid water , 1981 .

[13]  J. Hynes,et al.  Time-dependent fluorescence solvent shifts, dielectric friction, and nonequilibrium solvation in polar solvents , 1985 .

[14]  F. H. Long,et al.  Femtosecond studies of electron-cation geminate recombination in water , 1989 .

[15]  B. Berne,et al.  Behavior of the hydrated electron at different temperatures: structure and absorption spectrum , 1988 .

[16]  T. Goulet,et al.  Thermalization distances and times for subexcitation electrons in solid water , 1988 .

[17]  J. Wiesenfeld,et al.  Dynamics of electron solvation in liquid water , 1980 .

[18]  P. Wolynes,et al.  Smoluchowski–Vlasov theory of charge solvation dynamics , 1983 .

[19]  A. C. Chernovitz,et al.  Isotopic dependence of recombination kinetics in water , 1988 .

[20]  J. Boag,et al.  ABSORPTION SPECTRUM OF THE HYDRATED ELECTRON IN WATER AND IN AQUEOUS SOLUTIONS , 1962 .

[21]  E. Fielden,et al.  Primary radical yields and some rate constants in heavy water. , 1968, Radiation research.

[22]  P. Rossky,et al.  Electron localization in liquid water: A computer simulation study of microscopic trapping sites , 1986 .

[23]  R. Impey,et al.  Study of electron solvation in polar solvents using path integral calculations , 1986 .

[24]  J. Boag,et al.  Absorption Spectra in Irradiated Water and Some Solutions: Absorption Spectra of ‘Hydrated’ Electron , 1963, Nature.

[25]  P. Rossky,et al.  The hydrated electron: quantum simulation of structure, spectroscopy, and dynamics , 1988 .

[26]  J. Hunt,et al.  Solvation time of the electron in polar liquids. Water and alcohols , 1975 .

[27]  B. Berne.  A self‐consistent theory of rotational diffusion , 1975 .

[28]  Martin,et al.  Excess electrons in liquid water: First evidence of a prehydrated state with femtosecond lifetime. , 1987, Physical review letters.