The C ̃1Bu ← X ̃1Σg+ Transition of Ethanedinitrile (C2N2): Assignment of the Electronic State Origin and Vibrational Bands.

An analysis is presented for the vacuum ultraviolet C2N2 C̃1Bu ← X̃1Σg+ transition. Contrary to previous assumptions this is found to be a linear to bent transition with a trans-bent C1Bu excited electronic state. The band origin is at 59 840 cm-1. Vibrational bands between 170 and 145 nm are assigned. Vibrational frequencies for the C̃1Bu state are found to be ν1 = 2055 ± 20 cm-1 for the symmetric CN stretch, ν2 = 979 ± 20 cm-1 for the symmetric CC stretch, ν3 = 542 ± 10 cm-1 for the trans-bend, ν4 = 131 ± 10 cm-1 for the out-of-plane torsional bend, and ν6 = 141 ± 10 cm-1 for the cis-bend.