Fourier-transform microwave spectroscopy of N-methylaniline

The jet-cooled Fourier-transform microwave spectrum of N-methylaniline (C6H5-NHCH3) was recorded in the region of 10-26 GHz, and was analyzed to determine rotational constants and nuclear quadrupole coupling constants. Furthermore, a Coriolis-like coupling parameter characterizing an interaction between an internal rotation of a methyl group and an overall rotation was also determined from A-E splittings observed in pure rotational transitions with high Ka values. The Coriolis-like coupling parameter permitted the determination of the barrier to internal rotation of the methyl group which was found to be 975 cm−1.