THE MILLIMETER-WAVE SPECTRUM OF SRCCH(X(2)SIGMA(- CHEMICAL TRENDS IN METAL MONOACETYLIDE SPECIES()) )

The pure rotational spectrum of the SrCCH radical (X(2) Sigma(+)) has been recorded using millimeter/sub-mm direct absorption techniques. Sr CCH was synthesized in a de discharge by the reaction of strontium vap or, produced in a Broida-type oven, and acetylene. Seventeen rotationa l transitions of this molecule were recorded in the range 248-370 GHz and fine structure splittings resolved. Rotational and spin-rotation p arameters were determined using a (2) Sigma Hamiltonian. SrCCH appears to be linear with an ionic structure, as previously suggested. Compar ison of structural parameters with MgCCH and CaCCH suggest subtle diff erences in the bonding of these monoacetylide species.