Femtosecond photolysis of aqueous HOCl

This paper reports an experimental study of the photolysis of aqueous HOCl using femtosecond pulses at 266 nm. The formation of photoproducts is monit ored by transient absorption spectroscopy from 230 to 400 nm. The HOCl mole cules dissociate with unity quantum yield to form OH+Cl faster than 1 ps, a nd as a result of the potential along the HO-Cl reaction coordinate, all ex cess energy is given to the fragments as translational energy. After dissoc iation, and solvent cage escape, the majority of the Cl and OH fragments re combine after diffusion on a time scale of 50 ps. The diffusion dynamics is studied using a simple model for diffusive recombination and a more extens ive molecular dynamics simulation. A minor fraction of the Cl atoms (simila r to 10%) reacts with HOCl in a diffusion limited reaction to form Cl-2+OH. (C) 2001 American Institute of Physics.