Thermalization of low energy electrons in dielectric liquids

An experimental approach to determination of the rate of the electron energy loss has been developed for "hot" electrons in dielectric liquids. It is based on the measurements of d.c. two pulse photoconductivity of liquid solutions: at first, the UV laser pulse generates geminate electrons, trapped near their parent cations, through two photon ionization of admixed aromatic molecules, and then the second (probe) light pulse releases electrons from traps injecting the quasi-free electrons into the conduction band of liquid. For the anthracene solutions in methylcyclohexane the photoconductivity measurements have been carried out using the pulse dye laser to excite trapped electrons at wavelengths from 425 to 867 nm. The electron thermalization distances of 4.2 - 4.7 nm were determined for the photoelectrons with the initial kinetic energy within the range from about 0.9 to 2.4 eV. The electron impact ionization rate in hydrocarbon matrix is discussed.