title: The red-shift of surface plasmon absorption of 2D nanogold arrangement from disordered to ordered.
abstract: In this article, the changing of surface plasmon resonance (SPR) absorption of 2D arrangement of Au (3 nm) nanoparticles coated with 1-dodecanethiol (C12H25SH), obtained at different desolvation extents, had been investigated. It has been found that an obvious red-shifted happened when these arrays changed from loose, disordered to close-packed and ordered. Both transmission electron microscopy pictures and variation of SPR absorption of these arrays showed that the formation of long range two-dimension (2D) arrangement of nanoparticles coated with C12H25SH might be involved in two stages: At the first stage the particles can move freely and random patterns from loose to close package was driven by the Brownian Movement of solvated particles and as a result the voids were eliminated. The red shift of SPR absorption with the coverage (d lamda/d theta) is relative low. At the second stage, where the particles cannot move freely because of lack of solvent and a long-range two-dimension crystal was formed, the SPR shift to a longer wavelength with a larger d lamda/d theta. It is mainly attributed to the strong increase of the orientation and dipolar moment of the absorbed C12H25SH molecule on nanoparticles.
authors.affiliation: Key Laboratory of Colloid and Interface Science, Center of Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, People's Republic of China.
authors.forename: Junke
authors.initials: J
authors.lastname: Tang
authors.forename: Jinru
authors.initials: J
authors.lastname: Li
authors.forename: Huiling
authors.initials: H
authors.lastname: Rong
authors.forename: Bingsuo
authors.initials: B
authors.lastname: Zou
authors.forename: Long
authors.initials: L
authors.lastname: Jiang