Solvation ultrafast

Solvation, Ultrafast Photochemical Intramolecular Charge Transfer and... 

Solvation Ultrafast Dynamics of Reactions VIII. Acid-Base Reactions in Finite-Size Clusters of Naphthol in Ammonia, Water, and Piperidine, S. K. Kim, J. J. Breen, D. M. Willberg, L. W. Peng, A. Heikal, J. A. Syage, and A. H. Zewail, J. Phys. Chem. 99, 7421 (1995). 

Solid Saturated Hydrocarbons, Chemistry of Ionic Slates in (Kevan and Libby). Solvation, Ultrafast Photochemical Intramolecular Charge Transfer and Excited... 

Su, J.T. and Zewail, A.H. (1998) Solvation ultrafast dynamics of reactions. 14. Molecular dynamics and ab initio studies of charge-transfer reactions of iodine in benzene clusters. J. Phys. Chem. A, 102, 4082-4099. 

Kang T J, Yu J and Berg M 1990 Rapid solvation of a nonpolar solute measured by ultrafast transient hole burning Chem. Phys. Lett. 174 476-80... 

Ma J, Bout D V and Berg M 1995 Solvation dynamics studied by ultrafast transient hole burning J. Moi. Liq. 65/66 301-4... 

Lian T, Kholodenko Y and Hochstrasser R M 1995 Infrared probe of the solvent response to ultrafast solvation processes J. Rhys. Chem. 99 2546-51... 

Recently, Eisenthal and coworkers have developed time-resolved surface second harmonic techniques to probe dynamics of polar solvation and isomerization reactions occurring at liquid liquid, liquid air, and liquid solid interfaces [22]. As these experiments afford subpicosecond time resolution, they are analogous to ultrafast pump probe measurements. Specifically, they excite a dye molecule residing at the interface and follow its dynamics via the resonance enhance second harmonic signal. 

A. Elucidating the Influence of Solvation on the Site of Energy Absorption and Ensuing Ion-Molecule Reactions via Ultrafast Laser Pump-Probe Techniques... 

Femtosecond solvation dynamics experiments in water [147] clearly hint at the existence of a bimodal response of the solvent to a change in solute charge density that is produced by photon absorption for instance. Water appears to show an ultrafast component in the fl/ kT timescale and a slow component due to diffusive motions whose timescale would be in the 1/y range. 

The several theoretical and/or simulation methods developed for modelling the solvation phenomena can be applied to the treatment of solvent effects on chemical reactivity. A variety of systems - ranging from small molecules to very large ones, such as biomolecules [236-238], biological membranes [239] and polymers [240] -and problems - mechanism of organic reactions [25, 79, 223, 241-247], chemical reactions in supercritical fluids [216, 248-250], ultrafast spectroscopy [251-255], electrochemical processes [256, 257], proton transfer [74, 75, 231], electron transfer [76, 77, 104, 258-261], charge transfer reactions and complexes [262-264], molecular and ionic spectra and excited states [24, 265-268], solvent-induced polarizability [221, 269], reaction dynamics [28, 78, 270-276], isomerization [110, 277-279], tautomeric equilibrium [280-282], conformational changes [283], dissociation reactions [199, 200, 227], stability [284] - have been treated by these techniques. Some of these... 

Alfano, J. C., Walhout, P. K., Kimura, Y. and Barbara, P. F. Ultrafast transient-absorption spectroscopy of the aqueous solvated electron, J.Chem.Phys., 98 (1993), 5996-5998... 

However, picosecond resolution is insufficient to fully describe solvation dynamics. In fact, computer simulations have shown that in small-molecule solvents (e.g. acetonitrile, water, methyl chloride), the ultrafast part of solvation dynamics (< 300 fs) can be assigned to inertial motion of solvent molecules belonging to the first solvation layer, and can be described by a Gaussian func-tiona) b). An exponential term (or a sum of exponentials) must be added to take into account the contribution of rotational and translational diffusion motions. Therefore, C(t) can be written in the following form ... 

The immediate impact of this research will be a clearer understanding of ligand motions during photoelimination reactions. In particular, comparative studies of molecular motions in the gas phase (using ultrafast electron diffraction) and in the liquid phase should become a source of very detailed understanding of the influence of solvation on chemical processes. Such combined studies in collaboration with Peter Weber, Dept, of Chemistry, Brown University are planned. 

Finally, solute radical ions can be generated by light-induced, one-photon or multiphoton ionization of their parent compounds (Chaps. 5 and 16). This approach is particularly useful in the ultrafast studies of short-lived, unstable radical ions that aim to unravel their solvation, recombination, reaction, and vibrational relaxation dynamics of the primary charges (see, e.g., Chap. 10). Whereas the time scale of radiolytic production of secondary ions is always limited by the rate with which the primary species reacts with the dispersed parent molecules, light-induced charge separation can occur in <100 fsec. There are many studies on photoionization of solute molecules in liquid solutions we do not intend to review these works. 

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