Characterization of molecular motions in biomolecular systems by elastic incoherent neutron scattering.

In the present work the role played by the instrumental resolution function in elastic incoherent neutron scattering (EINS) experiment is discussed. An important result consists in the definition of an equivalent time t(), which depends both on the characteristic system time and on the resolution time, for which the spatial Fourier transform of EINS intensity profile and the self-distribution function (SDF) evaluated at t=t() are proportional. Then the equivalent time t(*) is introduced in the SDF procedure, an operational recipe for the mean square displacement determination. The new revised procedure is applied on data of myoglobin in trehalose dry environment and of hydrated homologous disaccharides (sucrose and trehalose).