Resonant vibrational excitation of methylamine by low energy electron impact

The study of the excitation functions of the NH2 and CH 3 stretching modes of methylamine in the 4-12 eV electron impact energy range shows evidence of a broad shape resonance built on the electronic ground state and centered at 7.5 eV. This resonance is formed by the trapping of the incident electron in the second unoccupied molecular orbital and is of A " symmetry. The elastic and inelastic angular differential cross sections measured in the 10°-90° range suggest a dominant p character. A second shape resonance located at higher energy contributes mainly to the enhancement of the CH3 deformation modes and is very likely of A ' symmetry. A comparison is made between the resonances observed in NH3 and CH 3 NH2. The effect of the methyl substitution is briefly discussed. © 1990 American Institute of Physics.