The 14N quadrupole hyperfine structure in the rotational spectrum of laser vaporized urea observed by molecular beam Fourier transform microwave spectroscopy

The microwave spectrum of urea has been recorded in the frequency range 8-19 GHz using a laser ablation molecular beam Fourier transform microwave spectrometer. The analysis of the nuclear quadrupole hyperfine splitting caused by two equivalent 14N nuclei yields the quadrupole coupling constants χaa = 2·205(26) MHz and χ bb = 1·8884(29) MHz. Seven different transitions transitions are reported. Distortion analysis is made with these seven plus 41 transitions previously published. We determine the rotational constants A = 11233·3161(87) MHz, B = 10369·4074(88) MHz, and C = 5416·6392(86) MHz and Watson's A reduced centrifugal distortion constants ΔJ = 10·58(37) kHz, Δ JK = -20·982(53) kHz, Δ K = 10·80(29) kHz, Δ J = 0·2208(43) kHz, and δ K = -14·6439(73) kHz.