LIGHT-INDUCED ELECTRON-EMISSION FROM POLYMETHYLPHENYL SILOXANE OILS

Light-induced electron emission from tetramethyl tetraphenyl trisiloxa ne, (Dow-Corning silicone oil DC704) and trimethyl pentaphenyl siloxan e (Wacker Chemie silicone oil AN175) has been measured as a function o f photon energy. Absolute quantum yield and threshold energy were dete rmined. The threshold energy of 7.5 eV for both siloxanes is comparabl e to the thresholds of other polymethylphenyl siloxanes with phenyl/me thyl ratios of 1/3 and 1/18, which were already investigated by the au thors. The quantum yield as a function of photon energy shows a system atic change with variation of the phenyl/methyl ratio. This dependence on the molecular structure is ascribed to a change of the initial ion ization quantum yield.