Slow relaxation process in DNA at different levels of hydration.
There are many speculations about the dynamic transition observed in hydrated bio-polymers at temperatures T ∼ 200 - 230 K being an important factor for enabling of their functions. The transition shows up as a sharp increase of atomic mean-squared displacements above this temperature. The nature of the dynamic transition is not yet clear. Using inelastic neutron scattering we show in this Note that the transition in DNA is related to the appearance of a slow relaxation process. Decrease in the hydration level suppresses the process and the dynamic transition. It is found that, in terms of dynamics, the decrease in water content is similar in effect to a decrease in temperature. The obtained results support the idea that the dynamic transition is mediated by the water of hydration since bulk water has a dynamic transition around the same temperature.
Department of Polymer Science, University of Akron, Akron, OH 44325-3909 USA.
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AP
Sokolov
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H
Grimm
A
A
Kisliuk
A J
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Dianoux