FTIR STUDIES OF CO-WATER COMPLEXES IN ARGON MATRICES AND IN POROUS ICES

Solid layers produced by the deposition at cryogenic temperatures of A r-H2O-CO and of CO-H2O mixtures have been investigated by FTIR spectro scopy. Effects of variations in concentration ratios, in deposition te mperature and of temperature cycling were studied. It is possible to a ssign all observed bands to single-component and to mixed (CO)(m)(H2O) (n) complexes. For the production of mixed species, higher deposition temperatures are more effective than temperature cycling. Formation is due more to H2O than to CO surface migration. Conclusions were applie d to a previous study of porous ices produced by temperature cycling o f noble gas-H2O solid mixtures onto which CO was deposited as a probe. They confirm that porous ices from Ar-H2O mixtures consist of small c lusters with 'surface porosity' and a large proportion of dangling OH bonds. The CO gets attached to more than a single OH bond. Ice so form ed from Ne-H2O mixtures has 'bulk porosity' with scattered free OH bon ds. Deposited CO penetrates it and forms small solid-like clusters or bonds to single OH bonds.