Quasielastic small-angle neutron scattering from heavy water solutions of cyclodextrins.
We present a model for quasielastic neutron scattering (QENS) by an aqueous solution of compact and inflexible molecules. This model accounts for time-dependent spatial pair correlations between the atoms of the same as well as of distinct molecules and includes all coherent and incoherent neutron scattering contributions. The extension of the static theory of the excluded volume effect [A. K. Soper, J. Phys.: Condens. Matter 9, 2399 (1997)] to the time-dependent (dynamic) case allows us to obtain simplified model expressions for QENS spectra in the low Q region in the uniform fluid approximation. The resulting expressions describe the quasielastic small-angle neutron scattering (QESANS) spectra of D(2)O solutions of native and methylated cyclodextrins well, yielding in particular translational and rotational diffusion coefficients of these compounds in aqueous solution. Finally, we discuss the full potential of the QESANS analysis (that is, beyond the uniform fluid approximation), in particular, the information on solute-solvent interactions (e.g., hydration shell properties) that such an analysis can provide, in principle.
Institute for Chemistry and Biochemistry/Crystallography, Freie Universität Berlin, Taku Str. 6, 14195 Berlin, Germany. a.kusmin@fz-juelich.de
André
A
Kusmin
Ruep E
RE
Lechner
Wolfram
W
Saenger
D003505:Cyclodextrins / Q000737:chemistry*; D017666:Deuterium Oxide / Q000737:chemistry*; D004058:Diffusion; D012399:Rotation; D053838:Scattering, Small Angle; D012996:Solutions; D014961:X-Ray Diffraction
D003505:Cyclodextrins; D012996:Solutions; D017666:Deuterium Oxide