The experimental liquid-phase spectrum of CH3NO2 from ref. 85 is reproduced in Fig. 7 for comparison. A weak peak appears around 1280 cm–1 corresponding to the 122 overtone. The small shoulder appearing in the experimental spectrum on the low-frequency side of the peak around 1400 cm–1 could be related to this overtone band. Other very weak peaks appear between 2700 cm–1 and 2850 cm–1 and are due to several different overtones and combination bands. These features could be related to the weak peak appearing in the experimental spectrum around the same frequency. A large number of features in the theoretical spectrum appear between 1600 and 2900 cm–1 and arise from the contributions of different combination and overtone bands.