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 various end groups, these are the cyanopolyynes HC₁₅N and HC₁₇N; the isocyanopolyynes HC₄NC and HC₆NC; the methylcyanopolyynes CH₃(C≡C)₃CN, CH₃(C≡C)₄CN, and CH₃(C≡C)₅CN; and the methylpolyynes CH₃(C≡C)₄H, CH₃(C≡C)₅H, CH₃(C≡C)₆H, and CH₃(C≡C)₇H. Measured line frequencies and derived spectroscopic constants are given for each. The microwave laboratory astrophysics of the entire set is now complete in the sense that all the astronomically most interesting rotational transitions, including those with nitrogen 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 astronomical discovery since they are closely related in structure and composition to ones that have already been discovered in space.