A Molecule with Small Rotational Constants Containing an Atom with a Large Nuclear Quadrupole Moment: The Microwave Spectrum of trans-1-iodoperfluoropropane

Using pulsed jet chirped-pulse, and cavity-based Fourier transform microwave spectroscopies over 900 transitions have been recorded for the title molecule in the 1-4 GHz and 8-18 GHz regions. the C ₁ , C ₂ and C _{3 carbon-13 species have been observed in natural abundance allowing a substitution structure for the CCC backbone to be determined. Nearly all the transitions observed were either a -type R branches or b -type Q branches. No c -type transitions were observed consistent with only the trans conformer being present under our experimental conditions. the χ aa , χ bb , χ cc and χ ab components of the iodine nuclear quadrupole coupling tensor have been determined. of note, several forbidden, Δ J ± 2 transitions, and one Δ J ± 3 transition were observed with quite reasonable intensity. These observations have been rationalized through considerations of near degeneracies between energy levels connected via a large χ ab ) value (≈1 GHz).}