5314027784

POSTER SESSION. H43

HIGH RESOLUTION FTIR SPECTRA OF THE BENDING FUNDAMENTALS AND OVERTONES OF DCCBr

R. BROTHERUS¹. O. YAITTINEN¹. L. HALONEN¹. O. POLANZ² AND H. BURGER²

¹ Laboratory of Physical Chemistry, P.O. Box 55 (A. I. Yirtasen aukio 1),

FIN-00014 University of Helsinki. Finland * FB9-Anorganische Chemie. Universitdt Gesamthochschule,

D-42097 Wuppertal. Germany

We have recorded high rcsolulion vibration-rotation spectra of deuterated monobromoacetylene (DCCBr) from 250 cm ¹ to 1000 cm'¹. The measurements were carried out with a Bruker IFS 120 HR spectromcter in Wuppertal and in Helsinki at a resolution of about 0.003 cm¹. The spectra show a high density of peaks due to several hot bands.

The recorded Vs, v₄, V3, v₄ + v_s and 2v₄ band systems have been rotationally analysed for both DCC⁷⁹Br and DCC^MBr isotopic species. Altogcther, 124 vibralion-rotation bands have been observed and accuratc rotational constants and vibration origins have been obtained for 33 vibrational States of both species. Paramcters for rotational /-resonance occuring between some States have also been determined. The results provided by the analysis have been used to build an energy level schcme for the low-lying vibrational States of DCCBr up to 2000 cm ¹ by using a vibrational Fermi resonance błock model. The model produces an RMS residual of 0.3 cni ¹ for the observed minus calculated vibrational wavenumbcrs.