Magnetic resonance studies of silver and related metal systems.

Electron Spin Resonance is used to detect radiolytically produced silver centres in a range of alkali halide:silver halide mixtures. A new silver aggregate electron excess centre is detected in mixtures of NaCl:AgCl containing high [Ag+] and a silver atom species is detected in a KF lattice where it appears to be coordinated asymmetrically to six fluoride ligands. The stability of Ag2+ as a hole centre in halide lattices is demonstrated. Silver centres in irradiated frozen solutions, as studied by ESR, can provide information on the solvation of the parent Ag+ ion. A solvation number of four for Ag+ in methyl cyanide is found and a solvation number of four or six in water seems likely. The spectra associated with other solvents are less informative, but some general conclusions regarding solvation and ion pairing are made. Silver atom-ion aggregates are frequently detected in these systems although aggregates of more than four silver nuclei are not found in any of the solvents studied. NMR results for cation induced shifts in the hydroxyl proton resonance in aqueous and methanolic solutions of a range -d10 metal cations support the view that the solvation number for Ag+ in these media is between four and six. An ESR study of radiation damage in a range of inorganic nitrates reveals a new paramagnetic nitrogen oxide or oxy-ion. So far unidentified, it appears to be similar to, but distinctly different from, NO3. Electron capture is studied in -d10 metal nitrates where there is a subtle balance between capture at cation and at anion sites; the paramagnetic centres in these nitrates often exhibit superhyperfine structure that can be linked to the crystal structures. The radiolysis of dinitrogentetroxide and the formation of N2O4+ and N2O4- is also studied.