Analysis of the CH 3D Nonad from 2000 to 3300 cm −1

Abstract

As part of the simultaneous analysis of line positions and intensities of the first two polyads of monodeuterated methane, the results achieved for the region 3–5 μm are reported. It involves the three highest fundamentals, (ν 1, ν 2, ν 4), overlapped by overtone (2ν 3, 2ν 5, 2ν 6) and combination (ν 3+ν 6, ν 3+ν 5, ν 5+ν 6) bands. The theoretical model was based on the global tensorial model implemented in the MIRS package. Some 10 000 line positions and 2400 line intensities have been modeled to ±0.000 88 cm −1 and ±3.6% respectively, using measurements obtained at 0.0056 and 0.011 cm −1 resolution with the Fourier transform spectrometer at National Solar Observatory located at Kitt Peak. The strongest band in this polyad is ν 4( E) at 3016.7 cm −1 with a strength of 6.3×10 −18 cm −1/(molecule cm −2) at 296 K; the weakest band is 2ν 3( E) at 2597.7 cm −1 with a strength of 1.9×10 −20 cm −1/(molecule cm −2) at 296 K. The total calculated absorption arising from the CH 3D nonad is 8.95×10 −18 cm −1/(molecule cm −2) at 296 K.