Weak Combination Bands in the 3-µm Region of Ethane.
The infrared spectrum of ethane in the region of the CH-stretching fundamental vibrations, between 2600 and 3300 cm(-1), was recorded with a Bruker IFS120HR Fourier transform spectrometer. Jet-cooled and room-temperature conditions were used at 0.01 and 0.005 cm(-1) instrumental resolution, respectively. Ten weak combination bands were observed and vibrationally assigned, in addition to the three principal bands in the region (nu(5), nu(7), and nu(8) + nu(11) ( parallel component)). A stack-by-stack analysis was performed for five of the combination bands. Their origins were determined as follows: nu(8) + nu(12) ( parallel component) at 2665.1512(30) cm(-1), nu(2) + nu(6) at 2753.326(32) cm(-1), nu(6) + nu(11) at 2844.13069(75) cm(-1), nu(8) + nu(11) ( perpendicular component) at 2930.705(90) cm(-1), and nu(4) + nu(10) at 3255.568(50) cm(-1). Effective rovibrational parameters were obtained for the corresponding upper states. New information was also obtained on the five remaining combination bands. Their approximate origins are: nu(8) + nu(12) ( perpendicular component) at 2660 cm(-1), nu(2) + nu(4) + nu(12) at 2860 cm(-1), nu(4) + 2nu(9) + nu(12) at 3090 cm(-1), 3nu(4) + nu(8) + nu(9) at 3157 cm(-1), and nu(4) + 2nu(8) at 3225 cm(-1). Copyright 1999 Academic Press.
Hepp
M
Laboratoire de Chimie Physique Moléculaire, Université Libre de Bruxelles, Brussels, B-1050, Belgium
Herman
M