RHEOOPTICAL CHARACTERIZATION (FLOW-BIREFRINGENCE AND FLOW-DICHROISM) OF THE TOBACCO-MOSAIC-VIRUS

Rheo-optical techniques of determining flow-birefringence Delta n' and flow-dichroism Delta n'' were employed to investigate a Tobacco Mosai c Virus (TMV) solution under steady-state and relaxation conditions to obtain further information about molecular dynamics in terms of local and global orientation and flexibility. These effects were investigat ed in a concentration range of 0,5 g/L less than or equal to c less th an or equal to 2,89 g/L, i. e. below and above the critical overlap co ncentration c = 2,45 g/L. Although some aggregation was unavoidable i t was determined that in the region of c the dynamic behaviour was no t influenced by varying the concentration. Furthermore it was shown th at these aggregates naturally appearing in TMV are sensitive to shear force and dissolve at shear rates above 1 s(-1). Beyond the critical s hear rate this rodlike molecule should show a good agreement of the or ientation angles determined through dichroism and birefringence and a constant ratio Delta n''/Delta n' which in fact was found. This reveal s experimentally that in spite of the sensitivity to different length scales dichroism and birefringence exhibit similar responses to shear forces for rigid and monodisperse macromolecules.