The Microwave Absorption Technique for Studying Ions and Ionic Processes

Microwaves propagating in a weakly conducting medium are attenuated. This effect can be used to study the yield and nature of the primary ionic species and their subsequent reactions in pulse ionised non polar media on a nanosecond timescale. Changes in conductivity of 5 × 10−9 ohm−1 cm−1 can be measured with a signal to noise ratio of 10. This corresponds to a concentration of less than 10−7 M of molecular ions (mobility ca 1 × 10−3 cm2V−1 s−1) in a liquid of viscosity 1 cP. The experimental requirements and theoretical background are discussed and a critical comparison is made with other techniques. Examples of the application of the method to some current problems in ionic processes are given.