THE REGION OF THE 3-NU-3 BAND OF METHANE

The spectrum of methane near 9000 cm-1, the region of the 3ν3 band, has been recorded at Meudon Observatory with a Fourier transform spectrometer under high resolution. Intensity measurements at two different temperatures, 149 and 295 K, have allowed us to identify two new vibration bands by determining the lower-state quantum numbers J of the transitions. About 100 lines are now assigned in this range, including P and Q branches. Furthermore, the first detailed rotational analysis of the 3ν3 band has been made; nine parameters of the band have been determined. The standard deviation of the differences between observed and computed wavenumbers for 45 lines of the 3ν3 band is only 0.045 cm-1. It is found that the observed 45 lines of the 3ν3 band correspond to the sublevel l3 = 3 and Cν = F 2. Copyright © 1980 by Academic Press, Inc.