Millimeter Wave Spectrum and Rovibrational Global Fit for Pyrrole

The free-jet millimeter wave absorption spectrum of pyrrole has been measured in the 59.6–78.3 GHz frequency range. The rotational spectra of four species have been assigned: the one for the normal species in both the vibrational ground state and the first excited state of the NH out-of-plane bending and those of two 13C monosubstituted isotopologues observed in natural abundance. For each species, the hyperfine structure due to the nuclear quadrupole coupling interaction of the 14N nucleus with the overall rotation has been resolved. The new rotational data for the ground state and the vibrational satellite were analyzed simultaneously with existing microwave/millimeter-wave data and rovibrational data for the fundamental [ν̃ = 474.647 552(5) cm−1], first overtone [ν̃ = 962.720 890(5) cm−1], and first hot bands of the NH out-of-plane bending motion. A comprehensive list of lines and the resulting set of spectroscopic parameters are provided.