The Millimeter-Wave Rotational Spectrum of CF3CCH in the Excited Vibrational State v10 = 2

The millimeter-wave rotational spectra of the excited vibrational state ν10 = 2 of the symmetric top species 3,3,3-trifluoropropyne (trifluoromethylacetylene), CF3CCH, have been recorded for J″ = 12 up to J″ = 34. The l = ±2 and l = 0 series have been assigned and the spectra analyzed to give rotational parameters including xll = 8260.44 MHz. The main interactions between states of different l are the rt(2, −1) and q+t (2, 2) interaction terms. Two types of l-resonance are identified, one of which is due to an avoided crossing between the l = 0 and l = 2 series.