Picosecond Pulse Radiolysis Study of Highly Concentrated Nitric Acid Solutions: Formation Mechanism of NO₃^• Radical

Abstract

The formation of nitrate radical, NO(3)(•), is observed for the first time directly by picosecond pulse radiolysis of highly concentrated nitric acid solutions. The experimental yield of NO(3)(-) ionization is deduced from the pulse-probe transient absorption measurements in the visible region where this radical absorbs. On the basis of the value of the extinction coefficient of nitrate radical at 640 nm equal to 1300 M cm(-1), the experimental yield of NO(3)(•) at 20 ps is found to be around 0.36 × 10(-7), 1.33 × 10(-7), and 2.85 × 10(-7) mol J(-1) for 1, 3.5, and 7 M nitric acid solutions, respectively. Relative to the dose absorbed by nitric acid by the direct effect, we find an unexpected high formation yield of the nitrate radical within the electron pulse. Therefore, we suggest that the trapping of the positive hole, H(2)O(•+), by NO(3)(-) also contributes to the formation of NO(3)(•) within the electron pulse. Moreover, after the pulse and within 4 ns, the beginning of the reaction of OH(•) radical with undissociated nitric acid is observed for the most concentrated nitric acid solution.

The low temperature radiolysis of cis-syn-cis- dicyclohexano-18-crown-6 complexes with alkaline earth metal nitrates: An evidence for energy transfer to the macrocyclic ligand

“…Both protonating the dianion NO 3 2− (reaction (9)) (Shkrob et al, 2011;Balcerzyk et al, 2012;Katsumura et al, 1991) and dissociative O 2 À transfer (reaction (10)) (Cook et al, 2001) have been proposed to explain the conversion of NO 3 2− to NO 2 . The resulting NO 2 radical reacts with DCH18C6 via H-atom abstraction from polyether ring to generate the macrocyclic -CH 2 -CḢ-O-radicals (reaction (11) …”

The Reactivity of the Nitrate Radical (• NO3 ) in Aqueous and Organic Solutions

“…The fuel dissolution is in aqueous nitric acid and is radioactive due to fission product and actinide decay. The • NO 3 radical is produced during the high‐energy irradiation of HNO 3 , and this radical may also act as an oxidizing agent for the organic ligands resulting in deleterious effects on solvent extraction performance in this condensed phase system.…”

Simulation of the radiation-chemical yields of hydrogen and hydrogen peroxide in concentrated solutions

“…), we found that the k Se2+X -k e+X and k SOH2+X -k OH+X rela tions can be expressed by: (18) A possible cause of the significant deviation of the values of k Se2+X for some systems ( Cu ++ ) shown in Table. [24] has to be considered. Since the processes of the formation and decay of NO 3 are not fully understood [25], it may be assumed that NO 3 can interfere in the H 2 formation process, scavenging electrons in the spurs:…”