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Rheo-optical techniques of determining flow-birefringence An' and flow-dichroism An" were employed to investigate a Tobacco Mosaic 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 investigated in a concentration range of 0,5 g/L < c 2,89 g/L, i. e. below and above the critical overlap concentration c* = 2,45 g/L. Although some aggregation was unavoidable it was determined that in the region of c* the dynamic behaviour was not influenced by varying the concentration. Furthermore it was shown that these aggregates naturally appearing in TMV are sensitive to shear force and dissolve at shear rates above 1 s-'. Beyond the critical shear rate this rodlike molecule should show a good agreement of the orientation angles determined through dichroism and birefringence and a constant ratio An"/An' which in fact was found. This reveals 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.

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