The Grotthuss mechanism

Suggested mechanisms for proton mobility are confronted with experimental findings and quantum mechanical calculations, indicating that no model is consistent with the existing data. It is suggested that the molecular mechanism behind prototropic mobility involves a periodic series of isomerizations between H9O4+ and H5O2+, the first trigerred by hyrdogen-bond cleavage of a second-shell water molecule and the second by the reverse, hydrogen-bond formation process.