The protonated species of water

Of all the possible autoionisation products of water the best known cations are the hydroxonium, HsO, and the H502, species. These ions are commonly reported in the structure of solid acids but spectroscopically they have remained somewhat elusive. This stems not from an inability to recognise the presence of the ions from the overall spectral response but rather to produce specific and reliable assignments for individual features. Occasionally rather unusual species like the tetrahedral H30 (written (Ho.75)40 [22] or [23] have been 

The structure and dynamics of these ions depend critically upon the local environmental details [6] and they are implicated in the mechanism of proton conduction in several materials. 

The overall assessment given in a recent review is probably still the simplest description of these ions, they are best regarded as clusters of one or more molecules of water associated with a more or less independent slave proton [28]. 

Vibrational spectroscopy with neutrons Table 9.2 The characteristic bands of H3O and Hs02 [26,27] (a). 

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