The major correction arising from the anharmonic treatment occurs for the frequencies, as also noted for the IR spectra. Anharmonic corrections do not modify significantly the relative intensities of the fundamental bands, except for the band at 1380 cm–1 corresponding to the νs(NO2) mode that is weakened by the anharmonic treatment for all three isotopomers relative to the harmonic model. However, for both of the deuterated isotopomers, a slight improvement in the intensities of the band corresponding to the 31 mode for the mono-deuterated and the 21 mode for the di-deuterated isotopomer (both corresponding to a stretching of the CD bonds) seems to appear from the anharmonic treatment, where they are reduced slightly more than the other bands that correspond to hydrogen-related motions. This modification of the relative intensities leads to somewhat better agreement with experiment.