Ion mobility measurements in a 50 cSt viscosity polydimethylsiloxane silicone oil

Using two different time-of-flight techniques (pulse voltage and V.U.V. photons pulse) ion mobility measurements have been performed, at room temperature, on a purified and direct 50 cSt polydimethylsiloxane silicone oil (Rhône Poulenc 604 V 50). These experiments have been carried out in a cell with plane parallel electrodes, for electric fields strengths ranging from 0.4 kV cm⁻¹ to 8 kV cm⁻¹ and for three electrode gaps(0.1 cm, 0.15 cm and 0.27 cm). The effect of some additives like N2O and C7F14 has also been investigated. The positive ion mobilities (≅ 6.2 10⁻⁵ cm²V⁻¹s⁻¹) are independent of the additives while, the negative ion mobilities decrease from 6.8 10⁻⁵ cm²V⁻¹s⁻¹ under N2 to 2.4 10⁻⁵ cm²V⁻¹s⁻¹ in presence of C7F14.