Field-dependent electron attachment in liquid tetramethylsilane

Abstract

Field-dependent attachment of quasifree electrons to carbon tetrachloride, CCl4, and ethyl bromide, EtBr, was observed in liquid tetramethylsilane (TMS) at 21 °C using a picosecond-pulse-conductivity technique. The field dependences of the electron-attachment rate constants, ke’s, of the two solutes, were measured at electric fields between 15 and 200 kV/cm and were found to parallel the energy dependences of the electron-attachment rates of the two scavengers in the gas phase; i.e., electron attachment to CCl4 decreases with increasing field (energy) whereas electron attachment to EtBr increases with increasing field (energy). The observed field dependence of the ke’s is interpreted as being consistent with electron heating by the field, and we estimate that a field of 150 kV/cm increases the energy of an electron in TMS at 21 °C to ∼0.1 eV. The effects of thermalizing third bodies on the field dependences of the ke’s are also discussed.