title: Insights into initial kinetic nucleation of gold nanocrystals.
abstract: Understanding the initial nucleation mechanism of monodisperse nanocrystals (NCs) during synthesis process is an important prerequisite to control the desired sizes and to manipulate the properties of nanoscale materials. The acquisition of information for the small nanocluster nucleation process, however, still remains challenging. Here, using a continuous-flow in situ X-ray absorption fine structure (XAFS) spectroscopy for time-resolved studies, we have clarified the initial kinetic nucleation of Au clusters under the grain size of 1 nm for the classical Au NCs synthesis via the reduction of AuCl(4)(-) in aqueous solution. The in situ XAFS results present the experimental revelation of the formation of intermediate Cl(3)(-)Au-AuCl(3)(-) dimer and the subsequent higher complexes 'Au(n)Cl(n+x)' in the initial nucleation stage. We propose a kinetic three-step mechanism involving the initial nucleation, slow growth, and eventual coalescence for the Au NCs formation, which may be helpful for the synthesis of metallic nanomaterials.
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yao
authors.forename: Zhihu
authors.initials: Z
authors.lastname: Sun
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Li
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Pan
authors.forename: He
authors.initials: H
authors.lastname: Wei
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
authors.forename: Masaharu
authors.initials: M
authors.lastname: Nomura
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Niwa
authors.forename: Wensheng
authors.initials: W
authors.lastname: Yan
authors.forename: Ziyu
authors.initials: Z
authors.lastname: Wu
authors.forename: Yong
authors.initials: Y
authors.lastname: Jiang
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Liu
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Wei