Oxygen ions, metastable

Metastable oxygen ions 02(a ITu) react fast with atoms or molecules (Ar, N2, CO, H2) in reactions that are endothermic with ground-state oxygen ions the respective rate constants do not depend much on translational energy. An interesting case is the charge-transfer reaction of electronically excited NO+(a S" ) with Ar The reaction is endothermic by 0.09 eV, and its rate constant increases with translational energy from the thermal value of 3 x 10 " cm s to a value of about 9 x 10 cm s at 3 eV in a way typical of... 

In view of the absence of the additional proton, the equivalent of the 341 ion, namely the 342 ion, would not be expected to be formed to any significant extent in the case of the oxygen-bridged compound. The fragmentation pattern confirms it and no metastable for this process was found. In the oxygen-bridged compound, metastables were observed at m/e 504.5, 357.5, 213, and 82.5. The processes responsible have been identified as ... 

The ion Cu" is extremely labile. Rate constants for the formation of maleate or fumarate complexes are =10 M s Ref. 281. It can be prepared in an acid perchlorate solution by reaction of Cu with a one-electron reducing agent such as Cr, or Eu Ref. 282. Although there is a marked tendency for disproportionation, solutions of Cu are metastable for hours in the absence of oxygen, particularly when concentrations of Cu(I) are low and the acidity is high. Espenson has capitalized on this to study the rates of reduction by Cu of some oxidants, particularly those of Co(III), Table 5.7 (see Prob. 6(c) Chap. 5). 

Fig. 14. Formation of metastable intermediate revealed in a classical molecular dynamics simulation of the decaniobate ion under basic conditions. Oxygen atoms are red, niobium atoms are green, and protons are white. The added hydroxide ion is represented by the yellow oxygen. Nbi is nucleophilically attacked by the hydroxide ion in (b), and the upper bond to the m3 and the bonds to the me oxygen atoms in the center of the ion are broken. The displaced niobium atom then proceeds to hydrate, with the waters represented by the blue oxygen atoms becoming progressively attached, and then hydrolyzing to release protons that can bind to other oxygen atoms on the decaniobate. Water molecules also hydrate the top Nb3 atoms as they become detached from the central m6 oxygen atoms after the Nb -m30 bond is ruptured.

The M-17 peak with the expected metastable ion was found to be a significant feature of the mass spectra of all substituted mono-TV-oxides examined and is assigned to a one-step elimination of the hydroxyl radical. For quinoxaline dioxides the M-16 peak is more important and is due to the preferential loss of an oxygen atom from the molecular ion.269... 

Photo-excited SO2 and SO2 clusters have been observed to undergo a number of excited state and ion-state processes. Ion-state studies have, for example, identified the energy threshold of the ion-state oxygen loss channel of the SO2 monomer and dimer [1], Additionally, studies investigating the metastable decay process of SO2 clusters and mixed S02-water clusters have identified the dissociation pathways and the nature of the charged core of these cationic clusters [2]. The dynamics of oxygen loss of SO2 and SO2 clusters following excitation to the C (2 A ) state, which couples to a repulsive state, have also been studied to determine the influence of the cluster environment on the dissociation process [3]. 

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