Thermalization of electrons by collisions with CCl4 in Ar buffer gas

The microwave conductivity signals produced by pulsed X-ray irradiation on a gas mixture of Ar (70 Torr) containing a trace amount of CCl4 at room temperature have been analyzed. The electron energy-loss rate coefficients for CCl4 and Ar as a function of the mean electron energy from 1 eV to near thermal energy are estimated to be about 10−7 and 10−13−10−14 cm3s−1, respectively. The thermalization times required for 1 eV electrons to reach 10% above thermal energy are 3 × 10−9 and 7 × 10−3 s at 1 Torr CCl4 and Ar, respectively. The exceptional effectiveness of CCl4 for electron thermalization is discussed.