Laboratory detection and submillimeter spectrum of NaCCH (x¹Σ)

Sodium monoacetylide has been observed in the laboratory for the first time using millimeter/submillimeter direct absorption techniques. The species was produced by the reaction of sodium vapor and acetylene under DC discharge conditions. Nineteen rotational transitions of NaCCH in its X 1£ ground state and 14 lines of the deuterium isotopomer NaCCD were recorded in the range 270-510 GHz. From these data, highly accurate rotational constants were determined. The detection of NaCN and NaCl in the envelope of the evolved carbon star IRC +10216 suggests that other sodium-bearing species may be present in this object.