Optical and Dynamical Properties of Chemically Synthesized Gold Nanoplates

• Published in: Journal of physical chemistry. C Vol. 117; no. 3; pp. 1447 - 1452
• Main Authors: Major, Todd A, Devadas, Mary Sajini, Lo, Shun Shang, Hartland, Gregory V
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 24.01.2013
• Subjects: Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Lattice dynamics; Nanocrystals and nanoparticles; 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; Phonons in low-dimensional structures and small particles; Physics; Surface and interface electron states; Scanning electron microscopy; Gold; Surface plasmon polariton; Nanoplate; Oscillations; Twinning; Surfactants; Chemical reduction; Monocrystals; Vibrational modes; Nanowires; Absorption spectra; Nanomaterial synthesis
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp311470t

Single crystal, micrometer-sized nanoplates were formed by reducing Au(III) in the presence of surfactants using a modified polyol protocol. The shapes of the plates range from triangular to hexagonal. The nanoplates have {111} surfaces with an average edge length of 5 ± 2 μm and an average width of 107 ± 30 nm. Scanning electron microscopy (SEM) images reveal that the plates grow through a re-entrant groove created by twinning. The optical properties of the plates were studied by scattered light and transient absorption experiments. The scattered light measurements show that propagating surface plasmon polariton (SPP) modes of the Au nanoplates can be excited when a laser beam is focused at the edge of the nanoplate. We also demonstrate that the direction of propagation of the SPP modes can be controlled through the polarization of the laser beam. The transient absorption traces for single suspended nanoplates show oscillations, which are assigned to thickness vibrations of the plates. The quality factors for the oscillations are smaller than those recently measured for suspended gold nanowires, indicating possible contributions to the vibrational damping from surface bound molecules or from the crystal structure.