The critical hydration reactions of NO+ and NO2+

Abstract

The reactions of NO ϩ and NO 2 ϩ with water are considered to make an important contribution to the formation of proton hydrates in the upper atmosphere. There have been several recent studies of the relevant reactions, with the result that discrepancies have arisen in each case over the critical number of water molecules required to promote the appearance of a proton hydrate. Presented here are new results based on the collision-induced reactions of NO ϩ •͑H 2 O͒ n and NO 2 ϩ •͑H 2 O͒ n cluster ions, which we believe clarify the situation.

Low-temperature fast atom bombardment mass spectra of frozen nitric acid-water solution

“…Some features of the LT FAB mass spectra are in agreement with the results obtained in a number of gas-phase studies of oxides of nitrogen and nitric acid. 20 -32 The limit of the maximum recorded size of hydrates of NO C and NO 2 C agrees with the notions of intracluster rearrangement leading to the formation and elimination of a neutral acid from a cluster of a certain size; 22 -30 the offset value of the cluster size (n > 4) which permits the retention of a neutral HNO 3 in the hydrate cluster HNO 3 Ð H 2 O n ÐH C also agrees with that found previously; 30 bell-shaped distributions of nitric acid hydrate clusters, produced from the solid, are similar to those obtained in the gas phase. 35 In the case of the crystalline hydrate of nitric acids, similarly to earlier reported results for hydrochloric acid and in contrast to some crystalline hydrates of salts, the production of clusters of water H 2 O n ÐH C is possible.…”

“…Another type of experiment enlightened the fate of larger clusters which can be formed from neutrals by means of the 'pickup' technique. 29,30 Processes similar to Eqns (1) and (2) were observed after ionization of the neutral clusters by electron impact (EI) 25 -30 or laser (photo-ionization). 24 Intracluster rearrangement and 'switching out' of a neutral acid were observed for H 2 O n ÐNO C with n > 3: 25 -27…”

Ab initio molecular dynamics simulation of aqueous solution of nitric oxide in different formal oxidation states

“…The formation of nitrous acid from the reaction of nitrosonium cation with water is also an important upper atmosphere reaction [61]. Experimental measurements [62] and gas phase ab initio calculations [63] have shown that this reaction is dominant when at least four water molecules is involved. The formation of nitrous acid in aqueous solution within 440 fs time scale shows that this reaction is essentially diffusion controlled with negligible energy barrier.…”

Thermodynamics of NO+·N2: Atmospheric Relevance

“…6 The suggestion that NO + ‚N 2 is the first complex ion to form, despite the fact that the binding energy of NO + ‚H 2 O is greater than that of NO + ‚N 2 , is due to the greater prevalence of N 2 versus H 2 O in the upper atmosphere. 1 To calculate accurately the equilibrium constant for the process it is desirable to know the binding energy of NO + ‚N 2 accurately.…”