Microwave spectra of 11 polyyne carbon chains

A summary is given of the laboratory study of the rotational spectra of 11 recently detected carbon chain molecules. Classified according to their var ious end groups, these are the cyanopolyynes HC15N and HC17N; the isocyanop olyynes HC,NC and HC,NC; the methylcyanopolyynes CH3(C--C)(3)CN, CH3(C drop C)(4)CN, and CH3(C dropC)(5)CN; and the methylpolyynes CH3(C dropC)(4)H, CH 3(C dropC)(6)H, and CH3(C dropC)(7)H. Measured line frequencies and derived spectroscopic constants are given for each. The microwave laboratory astro physics of the entire set is now complete in the sense that all the astrono mically most interesting rotational transitions, including those with nitro gen quadrupole hyperfine structure, have now been directly measured or can be calculated from the derived constants to a small fraction of 1 km s(-1) in equivalent radial velocity. All 11 carbon chains are candidates for astr onomical discovery since they are closely related in structure and composit ion to ones that have already been discovered in space.