Growth kinetics of PbS nanocrystals in organo-metallic Langmuir-Blodgett films studied by optical absorption spectroscopy

Abstract

Formation and growth of lead sulfide nanocrystals in lead stearate Langmuir-Blodgett (LB) films are investigated using the optical absorption spectroscopy method. The kinetics of changes in the concentration of lead ions in different states formed during the growth process, as well as the evolution of the nanocrystal average size versus growth time, are studied. Irrespective of the primary Pb2+ ion concentration in films, found was a nonlinear dependence of the nanoparticle growth rate vs time: at the initial stage the growth rate is higher than at the final one. The idea of diffusive decomposition of solid solution is used to analyze the experimental results. It is shown that high concentrations of metal ions at the interfaces of LB-film monolayers as well as diffusion restrictions of mass-transfer process play a decisive role in the formation and growth of nanocrystals in ordered organic matrixes.