Deuterium quadrupole coupling in rotational spectra of benzene-d₁ and of three isomers of fluorobenzene-d₁

Abstract

High resolution rotational spectra of benzene-d₁ and the para, meta and ortho isomers of fluorobenzene-d₁ have been recorded with a pulsed molecular beam Fabry-Perot cavity microwave Fourier transform spectrometer. Deuterium hyperfine splittings have been resolved for three rotational transitions of benzene-d₁ and for five to seven transitions of the isomers of fluorobenzene-d₁. The quadrupole coupling constant of deuterium along the C-D bond has been determined to be χ _zz = 186·1 (18) kHz for benzene-d₁, χ _zz = 187·7 (15) kHz and the asymmetry parameter η = 0·054 (18) for fluorobenzene-4-d₁, χ _zz = 190·9 (61) kHz and η = 0·079 (34) for fluorobenzene-3-d₁, and χ _zz = 187·6 (48) kHz and η = 0·042 (25) for fluorobenzene-2-d₁.