Internal dynamics of DNA probed by transient electric birefringence

Experiments on the field-free transient electric birefrigence decay of dilute solutions of monodisperse DNA fragments whose length L is much larger than the persistence length ${\mathit{L}}_{\mathit{p}}$ are reported. They reveal that the highly nonexponential decay is independent of L. We present a simple theoretical model which includes the internal rigidity of the polymer, explains the qualitative results of the measurements, and describes quantitatively the dynamics of long semiflexible polymers such as DNA, providing an accurate determination of the persistence length.