Incoherent quasielastic neutron scattering

The study of molecular dynamics in polymers is of great interest because the structural changes of the crystal lattice are intimately related to the onset of molecular motions which generate a special type of dynamical disorder within the crystals [101-104]. In this final section, we prerent an experimental account of the molecular dynamics of copolymers with 60/40 and 80/20 VF2/F3E mole fraction composition using incoherent quasielastic neutron scattering. 

Incoherent quasielastic neutron scattering measured as a function of hydration for powders of deuterated phycocyanin has been used to probe water motions (Middendorf et al., 1984). The simplest model accounting for the data was jump diffusion of water molecules between localized-sorption sites and the development of clusters of surface water at higher hydration (half-coverage of the surface, 0.15 h). This model is consistent with the picture developed from sorption thermodynamics. 

Feeney, M., Brown, C., Tsai, A., Neumann, D., and Deberedetti, PG. Incoherent quasielastic neutron scattering from fructose-water solutions, /. Phys. Chem. B, 105, 7799, 2001. 

Ewen B, Richter D (1978) Study of molecular motion in modifkation C of the n-alkane n-CjjHgg by means of incoherent quasielastic neutron scattering. J. Chem. Phys. 69 2954... 

Several techniques have been used to investigate dynamic properties of urea inclusion compounds, including solid-state NMR, incoherent quasielastic neutron scattering ESR, molecular dynamics simulation, Raman, infrared, dielectric loss, and x-ray diffraction. In addition to investigations of the dynamics of the guest molecules, the dynamic properties of the urea molecules have also been studied. 

In the nematic phase, the same timescales are operative. Although conformer probabilities are slightly shifted from the distribution in the isotropic liquid (more anisometric conformers are favored in the nematic), intramolecular isomerization rates are not influenced by the long-range orientational order. Incoherent, quasielastic neutron scattering gives the typically fast rotational diffusion about the principal axis 1, r 10 °-10 s. Reorientational flipping of the I axis is itself... 

Fig. 11. Measured incoherent quasielastic neutron scattering spectra of H2O confined phase in AIPO4-5 zeolite at T = 300K. The different water loading (20 %, 50 %, 90 % and 100 %) are deduced from the...

A. J. Leadbetter, F. P. Temme, A. Heidemann, and W. S. Howells, Self-diffusion tensor for two nematic liquid crystals from incoherent quasielastic neutron scattering at low momentum transfer, Chem. Phys. Lett. 34, 363-368 (1975). 

Computer simulations showed indeed that lipid molecules are jumping up and down. The mean width of the height distribution of the head groups in a phospholipid bilayer is typically 0.5 nm [1293, 1296]. Incoherent quasielastic neutron scattering on lipid bilayers indicated a smaller out-of-plane motion of 0.1-0.15 nm [1297]. 

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