The ground electronic state of 1,2-dichloroethane: II. Experimental investigation of the fundamental and overtone vibrations

The absorption spectrum of 1,2-dichloroethane has been recorded under various experimental conditions, between 50cm-1 and 10 000cm-1 using Fourier transform spectroscopy, and between 10 800cm-1 and 17 400cm-1 using optoacoustic laser spectroscopy. The assignment of the fundamental bands of the trans and gauche isomers was confirmed using in particular the results of recent ab initio calculations (El Youssoufi et al. 1998, Molec. Phys. 94, 461). The first overtone and combination bands were assigned for the first time using a variety of criteria including the band type and, in some cases, the spacing between clumps of rotational lines. Emphasis is placed on the CH progression of bands. Most of the results concern bands from the more abundant trans isomer, up to the near infrared range. Bands are tentatively assigned to the gauche species in the mid and near infrared regions and to the trans rotamer in the visible range. Vibrational frequencies and anharmonic parameters are obtained.