首页>
外文期刊>journal of chemical physics
>Dynamic light scattering from macromolecules: The separation of translation from rotational and deformational modes
【24h】
Dynamic light scattering from macromolecules: The separation of translation from rotational and deformational modes
展开▼
机译：Dynamic light scattering from macromolecules: The separation of translation from rotational and deformational modes
We consider the theory of dynamic light scattering from dilute solutions of macromolecules that undergo simultaneous translational, rotational, and conformational diffusion. Although the coupled diffusion problem is very difficult, we show that a relatively simple approximate theory is possible provided that the time scale for adjustment of the spatial position of the molecule is long relative to that characteristic of changes in the orientational and deformational configurations. After first developing a theoretical framework for the general case, we consider the case of rigidhyphen;rod macromolecules which was previously studied by other authors. In the present analysis we use a multiple time scale asymptotic technique which renders the solution of the coupled diffusion problem uniformly valid for both long and short times following some prescribed initial conformation. The resulting expression for the light scattering spectrum consists of a series of discrete exponentials in time (Lorentzians in frequency) rather than the more complex forms which were obtained by Maeda and Saito and Schaefferetal. The latter can, in fact, be obtained from the present theory in the limit of small correlation times. Comparison is made between the theoretically derived scattering spectrum and two available data sets for TMV. The indicated degree of anisotropy of the translational diffusion coefficient is the same for the two sets of data, but considerably smaller than expected from electron micrographs of TMV.
展开▼
