Autodetachment spectroscopy and dynamics of CH2CN− and CD2CN−

Abstract

The technique of autodetachment spectroscopy is utilized in a study of two electronic states of CH₂CN⁻ and CD₂CN⁻. The ground electronic state is a normal valence state while the outermost electron in the excited state is bound by the dipole moment of the neutral radical. Autodetachment occurs from excited rotational levels of this dipole bound state, giving some 5000 sharp features near the photodetachment threshold. All of these features were assigned and spectroscopic constants for both states are reported. The binding energy of the electron in this latter state is determined to be ≲66 cm⁻¹ and analysis of the autodetachment spectrum shows the electron affinities of CH₂CN and CD₂CN to be ∼12 500 and ∼12 430 cm⁻¹, respectively. The dynamics of the autodetachment process is studied and various mechanisms for detachment are described.