“…The pure rotational spectra of C 2 H 3 D were observed and analysed by microwave spectroscopy [6]. In this work [6], accurate rotational and centrifugal distortion constants in the ground state were determined, and the average structure of C 2 H 3 D molecule was also calculated. Most of the recent high resolution (at 0.004 cm À1 or better) FTIR studies on the ethylene molecules were focussed on C 2 H 4 [7,8], C 2 D 4 [9][10][11], trans-C 2 H 2 D 2 [12,13], cis-C 2 H 2 D 2 [14,15], and 1,1-ethylene-d 2 [16].…”