2013ApJ...762..121F

The A¹B₁ ← ¹A' excitation into the dipole-bound state of the cyanomethyl anion (CH₂CN^–) has been hypothesized as the carrier for one diffuse interstellar band. However, this particular molecular system has not been detected in the interstellar medium even though the related cyanomethyl radical and the isoelectronic ketenimine molecule have been found. In this study, we are employing the use of proven quartic force fields and second-order vibrational perturbation theory to compute accurate spectroscopic constants and fundamental vibrational frequencies for ¹A' CH₂CN^– in order to assist in laboratory studies and astronomical observations.