Protonated hydrates clustering energies

De Paz et have described recently a new technique with which cluster dissociation energies can be determined. Their study dealt with the proton hydrates H (H20) . The proton hydrates were produced by electron irradiation of water vapor in the 0.1-3-Torr range in the first ion source of a tandem mass spectrometer. The ion source of the second stage served as collision chamber and was filled with helium. Ions H (H20)fc formed by collisions of the primary H (H20) with He were detected with the second mass spectrometer. The energy required for the process... 

W. A. Donald and E.R. Williams, An improved cluster pair correlation method for obtaining the absolute proton hydration energy and enthalpy evaluated with an expanded data set, J. Phys. Chem. B 114 (2010), pp. 13189-13200. 

From the definition of acidity in solution as presented in Eq. (7.4), it is clear that in order to compute AG° one must know the proton solvation energy. However, from the previous discussion on the structural models for the hydrated proton one may anticipate some difficulties. For example, how many water molecules should be considered in the calculation of the proton solvation energy In other words How large should one take the H (H20) cluster One reasonable approach should be to examine the convergence of... 

Han et al. studied the dynamics of hydrated water molecules in NAFION by means of high-resolution MAS NMR measurements. Bound and free states of hydrated water clusters as well as the exchange protons were identified from the NMR chemical shift measurements, and their activation energies were obtained from the temperature-dependent laboratory- and rotating-frame spin-lattice relaxation measurements. Besides, a pecufiar motional transition in the ultralow frequency region was observed at 373 K for the free hydrated water from the rotating-frame NMR spin-lattice relaxation time measurements [60]. 

IR studies of the H20+.Ne open-shell complex were consistent with a planar, translinear proton-bound H-O-H-Ne geometry. Vibrational spectra were calculated ab initio methods) for the potential energy minima of the H30 (H20)4 cluster. FTIR data were used to follow low-temperature interconversions of sulfuric acid hydrates, H3O+HSO4 and [H502+]2S04 " at a variety of water partial pressures. ... 

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