Early Stages of ZnS Nanoparticle Growth Studied by In-Situ Stopped-Flow UV Absorption Spectroscopy The early stages of ZnS nanoparticle growth from supersaturated solution are investigated in situ by stopped-flow UV absorption spectroscopy with a time resolution of 1.28 ms. A model for data analysis is suggested which makes it possible to study both the average particle radius and the concentration. The average radii lie in the sub-nanometer range. During the first 40 ms, growth is predominantly governed by ripening. 2113-2119 2113-2119