Magnetic birefringence study of isotropic suspensions of tobacco mosaic virus

Publisher Website
Google Scholar
Abstract
The magnetic field induced birefringence in isotropic aqueous suspensions of tobacco mosaic virus (TMV) was measured as a function of temperature and concentration in high magnetic fields (100 kG). The temperature range was between 15 and 50 °C and the concentration range was between 4 and 20 mg/cm3. We find that the Cotton–Mouton constant (C) increases with decreasing temperature by 15%–20% over the entire range and extrapolates to infinity at a finite temperature of 110 to 150 K. At constant temperature, the measured ρ/C(ρ=number of TMV particles per cm3 of suspension) can be expanded in a power series of ρ, where the coefficients are expressed by the irreducible cluster integrals. At 20 °C the experimental values can be fitted to the linear form: ρ/λC=(2.09×1030–1.35×1015ρ)G2/cm3. For rigid cylindrical particles with l=3000 Å and d=180 Å, and using the rigid hard particle interaction model, we find for the first order coefficient 0.62×1015, i.e., a significant deviation for the rigid hard-rod model. This deviation is also indicated by the variation of C with temperature. We discuss the results on TMV and of similar measurements on phage fd in terms of the interparticle interaction and rigidity of the particles.