How inert is an argon matrix

Abstract SF 6 as an IR-active bulk and surface probe indicates the presence of porosity and diverse local environments in an Ar matrix prepared under experimental conditions favouring perfect isolation of guest molecules. This is in agreement with previous X-ray and neutron diffraction studies. A huge variety of different cage and surface sites are generated during formation of the matrix. On annealing, two generally contradictory phenomena occur: (a) perfectly isolated monomer species are enriched by sealing the micropores through which the monomers penetrated in the preceding deposition process; (b) cluster formation of SF 6 probes takes place, resulting in the appearance of extended crystalline phases in the larger pores and on the surfaces.