Knowledge Bank

We have observed a number of transitions of the short-lived radical CCH as well as the molecular ions $CO+,HN2+$, and $HCO+$ by means of millimeter and submillimeter wave spectroscopic techniques. Accurate spectroscopic parameters have been calculated from these data. CCH was first identified in the gas phase by Tucker, Kutner, and $Thaddeus1$ using radioastronomical techniques. Our work represents the first $reported2$ microwave spectroscopic detection of this species. For the detection of CCH and other elusive laboratory species, we find the spectral region around 300 GHz to be optimum.