Map of the Structural and Optical Properties of Gold Nanoparticles at Thermal Equilibrium

• Published in: Journal of physical chemistry. C Vol. 116; no. 26; pp. 14170 - 14175
• Main Authors: González, A. L, Noguez, C, Barnard, A. S
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 05.07.2012
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Nanocrystals and nanoparticles; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics; Structure of solids and liquids; crystallography; Nanoparticles; Gold; Phase diagrams; Property structure relationship; Microstructure; Crystal morphology; Extinction index; Crystal structure
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp3047906

The remarkable relationship among the size, shape, and optical properties of gold nanoparticles is proving to be very useful in a range of high-performance applications. Considerable effort and investment is focused on delivering gold nanoparticles with precise morphologies. However, the reliability of these particles is contingent upon the morphological stability, particularly against variations in the thermodynamic environment, such as changes in temperature. Presented here are results from a combination of computational and theoretical techniques showing how the optical properties of gold nanoparticles respond to changes in the size, shape, or temperature, obtained by sampling the optical spectrum over large configuration space, in accordance with the nanoscale phase diagram. We find that spectrum from morphologies expected at small sizes is robust against temperature fluctuations, unless the concentration is very high. At larger sizes, the color will likely change with temperature, due to the accompanying change in particle shape, and this change will be noticeable when the concentration is low.