2007ApJ...664L..43B

The negative molecular ion C₈H^– has been detected in the Galactic molecular source TMC-1. Four rotational transitions have been observed in the centimeter-wave band with the NRAO 100 m Green Bank Telescope (GBT) at precisely the frequencies calculated from the recent laboratory spectroscopy of this large carbon chain anion. C₈H^– is about 5% as abundant as C₈H, or somewhat more than C₆H^– relative to C₆ H (1.6%). Improved values of the column densities of C₆H^– and C₆H, and an upper limit for the abundance of the smaller carbon chain C₄H^– of 0.014% with respect to C₄H, have also been determined.