Neutron scattering experiments on magnetically aligned liquid crystalline DNA fragment solutions

Abstract

Small angle neutron scattering experiments have been performed on liquid crystalline 163 basepair NaDNA fragments in aqueous solution in the concentration range 190–285 mg ml⁻¹. To induce a macroscopic alignment, a magnetic field was applied either parallel (B _∥ configuration) or perpendicular (B _⊊ configuration) to the incoming neutron beam. The isotropic scattering pattern in the B _∥ configuration and the anisotropic scattering in the B _⊊ configuration agree with the cholesteric structure of the liquid crystalline solutions. From the anisotropic scattering in the B _⊊ configuration, information on the orientation ordering can be derived. For this purpose, the experimental data are compared to the form function of a uniform rod including a gaussian orientation distribution. The standard deviation of this distribution is approximately 20° for all concentrations investigated here.