Rotationally resolved A3Σu−–X3Σg− electronic transition of NC5N

The rotationally resolved A3Σu−–X3Σg− electronic spectrum of the NC5N radical has been observed in the gas phase by cavity ring down spectroscopy in a supersonic plasma. The origin band is at ν00=22 832.7(1) cm−1 and a rotational analysis gives constants B0″=0.02799(4) and B0′=0.02778(3) cm−1. These are compared to the Be values available from structures predicted by density functional theory and show that the molecule has a linear and centro-symmetric NCCCCCN structure.