Photodissociation caging dynamics

In order to probe the importance of van der Waals interactions between reactants and solvent, experiments in the gas-liqnid transition range appear to be mandatory. Time-resolved studies of the density dependence of the cage and clnster dynamics in halogen photodissociation are needed to extend earlier quantum yield studies which clearly demonstrated the importance of van der Waals clnstering at moderate gas densities [37, 111]... 

Wang W, Nelson K A, Xiao L and Coker D F 1994 Molecular dynamics simulation studies of solvent cage effects on photodissociation in condensed phases J. Chem. Phys. 101 9663-71... 

Photodissociation of a linear triatomic such as [85, 86] or Hgl2 [8] to produce a vibrationally excited diatomic, or cage recombination of a photodissociated diatomic such as I2 [78, 81] are classic model simple systems for reaction dynamics. Here we discuss tire Hgl2—>HgI + I reaction studied by Hochstrasser and co-workers [87, 88 and 89]. 

The concept of tunneling has recently been invoked to explain the mechanism of photodissociation of matrix-isolated molecules. Previously, photodissociation was customarily accounted for by the fact that transla-tionally hot photofragments escape from the cage and stabilize in separate matrix sites, thereby avoiding recombination. Using the time-dependent self-consistent field approximation for molecular dynamics simulations,... 

Cage effect dynamics or kinetics of geminate recombination was observed for the first time under photodissociation of aC C dimer of aromatic radicals in a viscous media. A suggestion has been made that at least in a number of smdied cases the mumal diffusion coefficient of radicals in the pair is approximately 10 times lower than the sum of macroscopic diffusion coefficients of the individual species. In other words, a geminate recombination proceeds considerably longer than expected. 

Schmidt, B. 1999, Quantum dynamics of HF photodissociation in icosahedral -Aii iHF clusters rotational control of the hydrogen cage exit . Chem. Phys. Lett. 301, 207. 

The photodissociation of I2 dissolved in CCI4 was studied (at a concentration of 29 x 10 3 mol/L). Although the process might look quite simple, it is actually quite complex. Several excited electronic states of I2 participates in the process and after the dissociation, the solvent cage may trap the atoms leading to geminate recombination or the atoms may escape from the solvent cage and recombine with other partners. With the time resolution available at a pulsed synchrotron source ( 100 ps), it is not possible to directly follow atomic motion, i.e., the dynamics of the chemical bond. Furthermore, it is expected that incoherent motion will set in... 

A. I. Krylov and R. B. Gerber,/. Chem. Phys., 100, 4242 (1994). Photodissociation of ICN in Solid and Liquid Ar" Dynamics of the Cage Effect and of Excited-State Isomerization. 

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