Quasielastic and inelastic neutron scattering in macromolecular solutions

We performed both quasielastic and inelastic neutron scattering, the latter extending to 1000 meV exchange energy, in pure water and in a solution containing 10% lysozyme by weight. The results obtained are discussed in the framework of a structured model of the solution, as given by many previous investigations made with optical techniques. In the case of pure water, our data agree perfectly with the results of others. For the lysozyme solution we found a strongly reduced mobility of water that also shows a ''trapped'' behavior in finite-size regions. As for the vibrational spectra, which involve high energy and high momentum transfer, we show that an appropriate analysis can be made using the ''impulse approximation'' for both pure water and solution cases. Again, such an analysis indicates the existence of a peculiar collective behavior of the macromolecular solution.