Photon-Induced Light Emission from Foamed Gold with Micro/Nanohollow Sphere Structures

We present a study on photon-induced light emission at room temperature from macroscale foamed gold with micro/nanoscale hollow spheres synthesized by seed-mediated growth method. Samples with a fixed sphere diameter but different Au densities are examined. It is demonstrated that strong and characteristic light emission from these samples can be achieved under optical excitation. In a short excitation wavelength regime (280-470 nm), the peak position in the photoemission spectrum increases almost linearly with excitation wavelength. In a relatively long-wavelength excitation regime (478-520 nm), photoluminescence (PL) can be observed where the peak position in the PL spectrum depends very little on excitation wavelength and two peaks can be seen in the PL emission spectrum. These effects do not change significantly with varying sample density, although it is found that the intensity of the light emission increases with sample density. We find that the features of the PL emission from foamed gold with micro/nanoscale hollow spheres differ significantly from those observed for Au nanoparticles. This study is relevant to the application of Au micro/nanostructures as advanced optoelectronic materials and devices.