Photolytic cage effect and atom recombination of iodine in compressed gases and liquids: Experiments and simple models

Quantum yields for photolysis of molecular iodine and recombination rate coefficients of iodine atoms were measured by nanosecond laser flash photolysis in the liquid solvents CO2, C2H6, C3H8, and n-heptane at pressures up to 5 kbar. The experiments continue earlier studies with these solvents performed in the gas phase at high pressures. The results are represented in terms of simple models which involve cage breakout, cage energy relaxation, stabilization in clusters, and diffusion control. Experimental studies over wide density ranges allow for a separation of the various components of the mechanism.