Absorption spectra of NO₃^- in solution

The nature of the electronic transitions, responsible for the absorption bands of NO₃^- in solution, is discussed. Environmental effects were studied to ascertain the type of transition responsible for the high intensity band. The effects detected on this band are entirely different from that displayed by electron-transfer band and hence it is assigned to internal transition, which is probably π→π. The effects studied are due to change of temperature, solvent and addition of various substances, mainly electrolytes. Ionic effects are discussed in view of the various types of ionic association. It is suggested that H-bonding plays a prominent role in the mechanism of these effects.