Quadrupolar relaxation of Ne-21, Kr-83, and Xe-131 dissolved in acetonitrile. A molecular dynamics study

To increase the understanding of quadrupolar relaxation of noble gases in solution, molecular dynamics simulations are carried out for a series of noble gas atoms dissolved in acetonitrile. The quadrupolar relaxation of Ne-21, Kr-83, and Xe-131 in a highly polar solvent is studied for the effects of the solute size. Temperature effects are investigated and the activation energies are calculated for the key motions in the relaxation. Structure and dynamics of the solvation shell around the three noble gas atoms are studied, and their role in intermolecular quadrupolar relaxation is examined. The simulation results are discussed in relation to various theoretical models, frequently used by the experimentalists. An electrostatic treatment is found to be applicable, given that the size dependence is correctly taken into account. The overall agreement of the simulation results with experimental data is good.