Radiation chemistry in occluded phases: MCM-41

Mixed-phase systems were designed by condensing hydrocarbons and halocarbon s into the 30 Angstrom pores of the silica tube material, MCM-41. Radical c ation probes, generated radiolytically at the phase interface with the sili ca wall or in the occluded phase inside the mesopores, were detected, as we ll as their paramagnetic reaction products, by variable-temperature EPR. Ch emistry of radical cations at the phase interface and in such confined phas es reveals the effects of energy transfer to solvent and geometric constrai nts on molecular packing and mobility. New, ordered forms of mesoporous sil ica offer many possibilities for studying the effects of nanoscale heteroge neity on radiation chemistry and on chemistry in general. (C) 2000 Elsevier Science Ltd. All rights reserved.