Free-Radical Conversions of Polymers Initiated by Nitrogen Trioxide

Free-Radical Conversions of Polymers Initiated by Nitrogen Trioxide 

Radicals of nitrogen trioxide (NO3) have a significant role in the chemical processes occnrring in the top layers of the atmosphere [1]. They are produced in the gas phase by the reaction of nitrogen dioxide (NO ) with ozone  

Dnring daylight, the primary loss mechanism of NO3 is by photolysis  

The NO3 radical has been produced via photolysis of solutions of ceric (IV) nitrates in mixtures of water with nitric acid (HNO3) [2-7] and acetic acid [8] as well as pure HNO3 [8]. Using flash photolysis of ceric ammonium nitrate (CAN) (NH ),Ce(N03) solutions, Martin and co-workers [2-5, 8] first postulated the primary photochemical process  

The ceric nitrate extinction coefficient is much lower in pure water then in HNOj solution. In the presence of HNO3, the ceric nitrate spectrum is red-shifted from that observed in water. This phenomenon is thought to result from the fact that the inner coordination sphere of Ce (IV) is occupied by OH groups in water or dilute HNO3 N03 in more concentrated HNO3 solution. The quantum yield for NO3 formation is constant for 5 M [HNO3] 14 M (tp 1), but tends to zero as [HNO3] 0. 

---