Diffusion and drift of electrons in dichlorodifluoromethane

The ratio of the diffusion coefficient to mobility, D /μ, and the drift velocity W of electrons in CCl 2 F 2 have been measured over the range 110< E/p <210 v cm −1 torr −1 at 20°C with gas pressures varying between 0·6 and 2 torr for electrode separations of 3 and 7 cm. A pulsed ultra-violet source was used for producing the initiatory electrons for the drift-velocity measurements which greatly improved the sensitivity of the method. In deriving D /μ, Moruzzi's data of Townsend's primary ionization and electron attachment coefficients α and η were used. A detailed theoretical analysis of errors indicates that the calculated D /μ values vary slightly with α and η. The close agreement between the evaluated D /μ values at the various pressures and electrode separations supports Moruzzi's data.