VISIBLE SPECTRUM OF DINITROGEN TRIOXIDE IN AQUEOUS-SOLUTION

The visible absorption spectrum of N2O3 has been measured by stopped-f low mixing of solutions of NaNO2 and HNO3. It has a maximum at 630 nm, epsilon = 29.3 dm(3) mol(-1) cm(-1). The spectrum is similar to that reported for solutions of N2O3 in anhydrous organic solvents at low te mperatures. Comparison with the blue species observed for solutions of NaNO2 in moderately concentrated HClO4 and HNO3 shows that although t he spectra are very similar there must be an additional species presen t in these very acidic media, possibly N2O3H+.