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采用光倒空技术对Na20和Na92团簇进行了光吸收实验,覆盖了近紫外部分以及可见光范围(2.0~5.5 eV);实验还研究了其它一些团簇在近紫外范围内的吸收截面.在可见光部分Na20的实验数据与现有的数据非常吻合.除了表面等离激元在可见光区域很强的吸收峰外,还观察到紫外区域明显的光吸收.对吸收截面光谱进行洛伦兹拟合揭示了中心略高于4 eV宽峰的存在,这个宽峰的频率与权重均与理论预测非常接近,被确定为纳米团簇“体等离激元”共振.这些吸收光谱是金属纳米团簇由光子激发的“体等离激元”集体电子态的首次实验观测与证实,这种实验现象只存在于有限体系.
The light-absorption experiments were carried out on the Na20 and Na92 clusters using the light-emptying technique, covering the near-ultraviolet region and the visible range (2.0-5.5 eV). The absorption cross section of some other clusters in the near UV range was also studied The experimental data of visible light part Na20 is in good agreement with the existing data.Except for the strong absorption peak of surface plasmon in the visible light region, significant light absorption in the ultraviolet region is also observed. The Lorentz-fit Reveals that the center is slightly above the 4 eV broad peak, and the frequency and weight of this broad peak are very close to theoretical predictions and are identified as nanoclusters. “The plasmon resonance” The first experimental observation and verification of the clusters by the photon excited “bulk plasmon” collective electronic states, this experimental phenomenon exists only in a finite system.