Knowledge Bank

The pure rotational spectrum for bromoperfluoroethane between 8.0 and 14.0 GHz and chloroperfluoroethane between 8.0 and 16.0 GHz has been measured on a chirped pulse Fourier transform microwave spectrometer for the first time. A total of 839 transitions for the bromoperfluoroethane, which includes the $\mathrm{<mrow\; data-mjx-texclass="ORD">79</mrow>}$Br, $\mathrm{<mrow\; data-mjx-texclass="ORD">81</mrow>}$Br parent isotopologues and the four $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}$C's, have been assigned quantum numbers. 496 transitions were observed for chloroperfluoroethane, which includes the $\mathrm{<mrow\; data-mjx-texclass="ORD">35</mrow>}$Cl and $\mathrm{<mrow\; data-mjx-texclass="ORD">37</mrow>}$Cl species. Only the $trans$ conformers were observed for which the rotational constants are reported. Nuclear electric quadrapole coupling constants have been determined and reported. Also, two dipole forbidden/quadrapole allowed $\Delta J$ = 2 transitions were observed in only the bromoperfluoroethane spectra. No forbidden transitions were observed in the chloroperfluoroethane.