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Light scattering from wormlike chains with excluded volume effects
Author(s) -
Sharp Phillip,
Bloomfield Victor A.
Publication year - 1968
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1968.360060814
Subject(s) - scattering , extrapolation , persistence length , chemistry , excluded volume , volume (thermodynamics) , small angle scattering , static light scattering , light scattering , scattering length , molecular physics , optics , physics , thermodynamics , molecule , statistics , mathematics , polymer , organic chemistry
This paper reports a calculation of the angular dependence of light scattering from wormlike chains with excluded volume effects. The Daniels distribution function, modified for excluded volume effects, is used to compute averages for scattering elements separated by contour lengths which are long with respect to the persistence length of the chain. An expansion in terms of exactly known moments of the distribution for the wormlike coil without excluded volume is used for short contour lengths. The results are applied to scattering from calf thymus ( M = 18.1 × 10 6 ) and T7 ( M = 25.4 × 10 6 ) DNA. It is demonstrated that the same values of excluded volume parameter (ε = 0.11) and statistical segment length (1/λ′ = 900 Å) which explain the sedimentation and viscosity behavior of DNA also account satisfactorily for the scattering behavior. Molecular weights and root‐mean‐square radii estimated by extrapolation from scattering data obtained in the angular region from 10° to 25° will be 5–10% too large for DNA of molecular weight 20 × 10 6 –30 × 10 6 .