Relaxational dynamics in dry and humid DNA

The influence of hydration on the self-correlation of DNA-hydrogens has been measured by using inelastic neutron scattering. The range of GHz to THz could be covered by combining back-scattering and time-of-flight data for long incident wavelength. The direct spectral response of water is masked by using D2O. Similar to other hydrated biopolymers, a steep increase of the susceptibility at low frequencies indicates a dynamic transition at T≊200 K. The difference for dry and humid DNA shows that the water molecules cause this transition.