The Estimation of the G-Values for Ionization and Excitation of Ten-Electron Molecules: Methane, Ammonia, and Water Irradiated by 100 keV Electrons

The binary-encounter collision theory is applied to calculate the G-values for the ionization and excitation of methane, ammonia, and water irradiated by 100 keV electrons. Double collision of the incident electron in a molecule is also taken into account. On the assumption of the occurrence of certain reactions in the systems, the G-values for electrons, various radicals, and several final products were estimated. Some of the results are as follows: the G-values for electrons were 3.60 for methane, 3.56 for ammonia, and 3.00 for water. These values are in fair agreement with the experimental values: 3.6 for methane, 3.8 for ammonia, and 3.3 for water. The calculated G-value for hot hydrogen atoms was about 1.0 for all three compounds. The ratios of the G-value for excitation to that for electrons are 1.1 for methane, 1.5 for ammonia, and 1.7 for water. An estimation was also made of the G-value for the emission of highly-excited hydrogen atoms using reported cross sections. The G-values are 0.1 for methane and ammonia, and 0.2 for water.