Quasi-elastic neutron scattering self-diffusion coefficients

A. Comparison of Self-Diffusion Coefficients Determined by Pulsed-Field Gradient NMR and Quasi-elastic Neutron Scattering... 

Nowikow et al. (1999) measured the self diffusion of water in 0.94 m BU4NCI at room temperature using quasi-elastic neutron scattering. The residence times of water molecules in the hydration shell of the cation were twice longer than in bulk water. Still, (1 - Z>w(E)/-Dw) > 0 and the salt is a net structure maker. Sacco et al. (1994) measured the self diffusion coefficient of the water in aqueous CsCl in D2O... 

Therefore, knowledge of these scattCTing and spectroscopic methods applied to ionic solutions is quite useful for clay-water-ion interface simulations. They discussed the utility of the computational results directly comparable to the scattering and spectroscopic methods. These includes radial distribution function comparison (MD or MC with X-ray or neutron diffraction methods), angular distribution of water molecules around ions (MD or MC with neutron diffraction measurements), self-diffusion coefficient of water and ions (MD with quasi-elastic neutron scattering and NMR measurements), and intramolecular vibrations (flexible potential MD with IR or Raman spectroscopic data). 

It is possible to examine experimentally both the diffusion in a liquid crystal of its own molecules (self-diffusion) and the diffusion of impurities. The coefficients of self-diffusion are determined by various methods, e.g., quasi-elastic neutron scattering [100], the diffusion of tracer (radioactive) molecules [101], or the spin-echo methods in nuclear magnetic resonance spectroscopy [102]. The last method is probably the most reliable. Essentially, it is as follows initially the spins of the molecular protons are polarized by a marked pulse of a radio-frequency field then the molecules... 

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