Large Au nanoplates were synthesized by reduction of HAuCl4 in the presence of PVP and CTAB. The nanoplates were either hexagonal or triangular in shape, and were found to be single crystalline with {111} faces by XRD analysis. The average length of the nanoplates was 5 � 2 �m and the average thickness was 107 � 30 nm. Scanning Electron Microscopy (SEM) images suggest the nanoplates grow through a re-entrant groove created by twinning. Scattering light, near-field scanning optical microscopy (NSOM) and transient absorption measurements were taken of individual Au nanoplates to identify their optical properties. Scattering light experiments reveal that the propagating Surface Plasmon Polariton (SPP) can be excited by edges of the nanoplates, and their direction can be controlled by changing the polarization of the laser beam. NSOM images of the nanoplates shows a Fabry-Perot type interference which can be seen when exciting the edge of plates with a continuous wave laser. These interferences disappear when the polarization of the laser is perpendicular to the excited edge. Transient absorption measurements of suspended Au nanoplates shows an oscillatory signal, which corresponds to thickness vibrations of the nanoplates. The quality factors of the oscillations were lower than previously measured for other nanomaterials, suggesting that the quasi two-dimensional shape could increase the damping of these vibrations. Future work with these nanoplates will include nanofabrication of single crystalline nanowires with square-shaped cross sections for acoustic measurements, as well as use for nano-antennas to controllably direct or focus plasmons through 2-dimensional structures.

Dynamical and optical properties of gold nanoplates

246th National Meeting (2013)

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