Hypersonic Vibrations of Ag@SiO2 (Cubic Core)−Shell Nanospheres
| Autor: | Zhikui Wang, Hock Siah Lim, Xianmao Lu, Ser Choon Ng, Meng Hau Kuok, Toan Trong Tran, Jing Ya Sun |
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| Rok vydání: | 2010 |
| Předmět: |
Silver
Materials science business.industry Finite Element Analysis Dispersity General Engineering Physics::Optics General Physics and Astronomy Nanoparticle Acoustics Silicon Dioxide Vibration Molecular physics Light scattering Brillouin zone Core (optical fiber) Optics Molecular vibration General Materials Science Particle size Particle Size business Nanospheres Plasmon |
| Zdroj: | ACS Nano. 4:7692-7698 |
| ISSN: | 1936-086X 1936-0851 |
| DOI: | 10.1021/nn102581g |
| Popis: | The intriguing optical and catalytic properties of metal-silica core-shell nanoparticles, inherited from their plasmonic metallic cores together with the rich surface chemistry and increased stability offered by their silica shells, have enabled a wide variety of applications. In this work, we investigate the confined vibrational modes of a series of monodisperse Ag@SiO(2) (cubic core)-shell nanospheres synthesized using a modified Stöber sol-gel method. The particle-size dependence of their mode frequencies has been mapped by Brillouin light scattering, a powerful tool for probing hypersonic vibrations. Unlike the larger particles, the observed spheroidal-like mode frequencies of the smaller ones do not scale with inverse diameter. Interestingly, the onset of the deviation from this linearity occurs at a smaller particle size for higher-energy modes than for lower-energy ones. Finite element simulations show that the mode displacement profiles of the Ag@SiO(2) core-shells closely resemble those of a homogeneous SiO(2) sphere. Simulations have also been performed to ascertain the effects that the core shape and the relative hardness of the core and shell materials have on the vibrations of the core-shell as a whole. As the vibrational modes of a particle have a bearing on its thermal and mechanical properties, the findings would be of value in designing core-shell nanostructures with customized thermal and mechanical characteristics. |
| Databáze: | OpenAIRE |
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