The VPT analysis shows that the structure below the vibrational origin results primarily from anharmonic coupling within the anion, whereas above the origin the quartets corresponding to the 3 sequence band mostly reflect neutral anharmonic couplings. In fact, three of the peaks within these quartets can be considered to be polyads based on the 3=1 neutral level, while the fourth peak results from photodetachment to neutral states involving 𝜈 4 + 𝜈 8 excitation.