Characterization of electronically excited states in anionic acetonitrile clusters

We have identified and examined the excited state of the cluster-solvated, valence-bound acetonitrile anion dimer, consistent with recent experimental findings, determining that the cluster excited state is of predominantly single-excitation character. Potential energy surface scans in coordinates specific to a "dissociative" normal mode common between the excited and ground states of the valence anion as well as the ground-state neutral dimer species shed light on the proposed vibrational autodetachment mechanism, with calculated excited-state lifetime consistent with experiment.