DYNAMIC LIGHT-SCATTERING-STUDIES OF BASIC DIISOBUTYL ZINC DITHIOPHOSPHATE

Dynamic light scattering (DLS) techniques have been applied to the stu dy of basic diisobutyl zinc dithiophosphate (ZnDTP) salt. The translat ional diffusion coefficient of basic diisobutyl ZnDTP in hexane was me asured. The experimental data were analyzed using the method of CONTIN . The above approach yields a value for the site of basic diisobutyl Z nDTP that is consistent with X-ray data. Using the simplest approach o f Stokes-Einstein where the tetrahedral solid-state structure is appro ximated as a sphere, the DLS data suggest that the diameter of the par ticle is approximate to 16 Angstrom. A more refined hydrodynamic model , accessible surface area (ASA), was also applied to this molecule. Th ese hydrodynamic slip calculations yield a diffusion coefficient for t he basic zinc diisobutyl ZnDTP salt that is somewhat larger than that for the experimentally derived translational diffusion coefficient. Po ssible reasons for the discrepancy are discussed.