Low-energy electron attachment to molecules studied by pulse-radiolysis microwave-cavity technique combined with microwave heating

A new experimental technique has been developed to study electron-energy dependence of the electron attachment to molecules. Time dependence of electron density is measured by conventional pulse-radiolysis microwave-cavity method, and a microwave heating technique is additionally applied in order to vary the mean electron energy from thermal to several electronvolts. The calibration of the mean electron energy is made by analyzing the time profile of microwave conductivity signals for thermalizing electrons produced by pulsed x rays in gaseous Xe which shows the Ramsauer minimum in the momentum-transfer cross sections in collisions with electrons. Presented are rate constants for electron attachment to SF6, CCl4, CHCl3, CFCl3, CF3I, CF3Br, 1,1,1-C2F3Cl3, and 1,1,1,-C2H3Cl3 measured in the electron-energy range from thermal to about 2 eV. The data are discussed in conjunction with previous data obtained by different experimental methods.