1998A&A...335L...1G

We report the detection of the elusive carbon-chain radical C₅N in the dark cloud TMC1 and its tentative detection in the circumstellar envelope IRC+10216. C₅N appears to be two orders of magnitude less abundant than the related molecule HC₅N and much less abundant than expected from current gas phase chemistry models. In comparison the HC₃N to C₃N abundance ratio is of the order of 10, in reasonable agreement with model predictions. We have also detected in IRC+10216 two lines arising from the C₃H radical in its excited ν₄=1 state.