Investigating the Shape Evolution Mechanism of CdSe Quantum Dots by Chemometrics Analysis of Spectrophotometric Data

Abstract

The study on the mechanism of the shape evolution of nanocrystaline particles is an important and emerging field, which is applicable in the shaped control synthesis of nanoparticles. As an alternative to transmittance electron microscopy (TEM), which is already used in the study of nanoparticles, in this article a simple spectrophotometric method has been proposed utilizing the advantages of chemometrics methods in analyzing overlapped and complex spectral data. The evolutionary visible absorbance data of CdSe quantum dots through particle formation were analyzed by factor analysis, evolving factor analysis, and multivariate curve resolution−alternative least-squares analysis, by which four chemical factors, attributed to the CdSe nanoparticles of different shapes, were detected and the concentration profiles and pure spectra of these particles were resolved. The interpretation of the evolution profiles of the detected nanocrystaline CdSe particles was easily achieved by using the existing shape evolution mechanism. The formation of magic size nanoclusters was detected at the beginning of the reaction, which was followed by the formation of rods and other elongated particles. At the end of the reaction, the formation of thermodynamically stable quantum dots nanoparticles was identified.