Production of negative ions from CH3X molecules (CH3NO2, CH3CN, CH3I, CH3Br) by electron impact and by collisions with atoms in excited Rydberg states

Thermal electron attachment to nitromethane, methylcyanide, methyliodide, and methylbromide is compared with capture of electrons by these molecules from highly excited Rydberg states of atoms. Data on thermal electron attachment to CH3NO2 are consistent with a three-body attachment process, with the nature of the third body being important. The thermal energy electron attachment rate constant for CH3CN is ≤1.24×10−14 cm3 sec−1. Some results on dissociative electron attachment and ion pairing processes in CH3NO2, CH3CN, CH3I, and CH3Br are also presented.