Vibrational spectrum of gaseous N2O3

Gaseous N2O3 was produced by the equilibrium reaction of NO with NO2. By careful selection of the temperature and pressure the relative concentration of N2O3 was high and its infrared spectrum was obtained without interference from other nitrogen oxide absorptions. The spectrum reveals new features previously unreported including sequence bands containing torsional vibrations. This work, together with other far infrared studies, provides an assignment of all the N2O3 vibrational frequencies. An estimate of the internal rotation potential function indicates a barrier height of the order of 1 kcal/mole.