The Infrared and Raman Spectra of Condensed Nitric Oxide

The infrared and Raman spectra of liquid and solid nitric oxide have been studied in an attempt to prove the existence of the (NO)2 molecule. The liquid has four strong Raman lines at 1861, 262, 196, and 167 cm−1; two weaker Raman lines at 1760 and 487 cm−1; and two strong infrared bands at 1863 and 1770 cm−1. Several weaker infrared bands can be satisfactorily assigned as combinations by using the observed strong infrared and Raman frequencies. The spectra were found to be due exclusively to a dimer which probably exists as a bent ONNO molecule.