Experimental evidence for the rough hard sphere model of liquids by high pressure NMR

摘要

The NMR19F spinndash;lattice relaxation times, selfhyphen;diffusion constants, and densities have been measured in liquid CCl3F as a function of temperature and pressure. Since spinndash;rotation interactions provide the dominant relaxation mechanism for fluorine nucleus, the analysis of theT1data yields the angular momentum correlation time tgr;J. The density dependence for the spinndash;rotation relaxation data enables us to calculate the effective hard sphere diameter for liquid CFCl3. In turn these diameters are used in calculation of the selfhyphen;diffusion constants applying the rough hard sphere model for molecular liquids as recently proposed by Chandler. Our experimental results provide evidence for (i) relationship between tgr;Jand the Enskog relaxation time tgr;E; (ii) validity of the rough hard sphere model for fluids; and (iii) the dependence of diffusion constants upon density in agreement with molecular dynamics calculations by Alderetal.