Breaking a tetrahedral molecular ion with electrons: study of NH⁺₄

Abstract

We apply a general theoretical model to study the dissociative recombination of the polyatomic ion NH+4. The high symmetry of the molecule, represented by the tetrahedral group, leads to complex vibronic couplings responsible for dissociative recombination. By applying multi-channel quantum defect theory and using symmetry considerations, we treat the doubly and triply degenerate modes and electronic states of NH+4 to calculate a theoretical cross section. The cross section agrees well with existing experimental data.