Knowledge Bank

In contrast with that cyanopolyynes have been detected in laboratory up to $HC17N$ and in interstellar space up to $HC11N$, our knowledge on the linear form of $HCnN$ with even n number has been limited to only the HCCN radical by laboratory detection and interstellar observation. We report here a detection of the $HC4N$ radical in its triplet electronic ground state in the discharge of $HC3N$ (0.2%) diluted in Ar. A Fourier-transform microwave spectrometer equipped with a pulsed-discharge $nozzlea$ has been used. The combination of discharge mixtures, the rotational structure, and the fine and hyperfine structure that is similar to the HCCN radical all indicated that the carrier of the spectrum is $HC4N$ with linear or quasilinear structure. Progress on the characterization of this new radical will be presented.