Molecular beam pulsed-discharge Fourier transform microwave spectra of CH3–CC–F, CH3–(CC)2–F, and CH3–(CC)3–F

The methylfluoroacetylenes CH3–(CC)2–F and CH3–(CC)3–F have been generated for the first time in a pulsed-discharge nozzle and characterized by molecular beam Fourier transform microwave spectroscopy in the 5–26 GHz frequency range. The spectroscopic constants B=1086.44824(13) MHz, DJ=0.02044(70) kHz, and DJK=7.083(91) kHz of CH3–(CC)2–F and B=478.908444(34) MHz, DJ=0.003060(98) kHz, and DJK=1.899(22) kHz of CH3–(CC)3–F have been determined. In addition, the 13C isotopic species of CH3–CC–F in their natural abundances have been measured, and a partial substitution structure of CH3–CC–F has been derived and compared with those of related fluorine derivatives.