A Radiation-Induced Bonding of Iodine at the Surface of Uniform Polystyrene Particles

Abstract

At a population of 1.4 X 1012 particles of 0.234-um diameter cc-', the yield of surfacebonded halogen in 5 X 10-4 M iodide corresponds to 0.02 iodine atoms bonded to the particle surface per 100 eV of total energy absorbed. In 5 X 10-4 M iodide, the reaction rate is proportional to the surface area and depends upon the first power of the radiation intensity. The experimental results are consistent with a reaction mechanism in which radical sites are produced on the particle surface by reaction of OH and other radicals from the bulk phase. A surface bonding of iodine results from a reaction of these sites with halogen intermediates formed in the aqueous phase, predominantly by reaction of OH radicals with iodide. Energy absorbed in the particle apparently plays no major role in the reaction, and a complex dependence of the reaction upon the iodide concentration suggests that a surface adsorption of halogen intermediates plays an important role in the reaction.