Optical properties of nanostructured thin films containing noble metal clusters: Au_N, (Au_0.5Ag_0.5)_N and Ag_N

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• 作者：Pr&eacute ; vel ; B. ; Lerm&eacute ; J. ; Gaudry ; M. ; Cottancin ; E. ; Pellarin ; M. ; Treilleux ; M. ; et. al.
• 关键词：Optical spectroscopy ; Optical properties ; Metals ; Surface plasmon resonance
• 刊名：Scripta Materialia
• 出版年：2001
• 出版时间：May 18, 2001
• 年：2001
• 卷：44
• 期：8-9
• 页码：1235-1238
• 全文大小：223 K

文摘

The optical properties of nanocomposite thin films of gold, silver and bimetallic silver-gold clusters embedded in a porous alumina matrix have been investigated in the size range 2–6.7 nm. The metallic particles are produced by laser vaporization of either an Au_0.5Ag_0.5 alloy or a pure metal target whereas the dielectric matrix is evaporated by an electron gun. Samples involving a low metal concentration have been characterized by several complementary techniques in order to determine their composition, morphology and cluster size distribution. The mixed particles have the same stoichiometry as the target rod. Optical absorption spectra exhibit a surface plasmon resonance whose position is shifting with cluster mean size, giving evidence of finite size effects. Theoretical calculations in the framework of Time-Dependent-Local-Density-Approximation (TDLDA), taking into account an inner skin of ineffective screening and the porosity of the matrix, are consistent with observed size evolutions of the Mie frequency in each type of sample.