  The dipole-bound excited state of the methylene nitrile anion (CH2CN-) has
been suggested as a candidate carrier for a diffuse interstellar band (DIB) at
803.8 nm. Its corresponding radical has been detected in the interstellar
medium (ISM), making the existence for the anion possible. This work applies
state-of-the-art ab initio methods such as coupled cluster theory to reproduce
accurately the electronic excitations for CH2CN- and the similar methylene
enolate anion, CH2CHO-. This same approach has been employed to indicate that
19 other anions may possess electronically excited states, five of which are
valence in nature. Concurrently, in order to assist in the detection of these
anions in the ISM, work has also been directed towards predicting vibrational
frequencies and spectroscopic constants for these anions through the use of
quartic force fields (QFFs). Theoretical rovibrational work on anions has thus
far included studies of CH2CN-, C3H-, and is currently ongoing for similar
systems.
