Stamplecoskie Kevin G, Kamat Prashant V
Notre Dame Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.
J Phys Chem Lett. 2015 May 21;6(10):1870-5. doi: 10.1021/acs.jpclett.5b00665. Epub 2015 May 6.
When molecules or clusters are within the proximity of metal particles, their electronic transitions can be drastically enhanced. We have now probed the off-resonance excitation of molecule-like, glutathione-capped gold clusters (Au-GSH) in the close proximity of larger (plasmonic) Au and Ag nanoparticles. The excited state absorption spectrum of Au-GSH* is obtained with monophotonic excitation. The characteristic absorption of Au-GSH* allows us to probe the influence of excited plasmonic nanoparticles coupled with the clusters. Although infrared (775 nm) lasers pulses do not produce Au-GSH*, the excited states of these clusters are formed when coupled with metal (Au, Ag) nanoparticles. Interestingly, the coupled excitation of Au-GSH/AgNP with 775 nm laser pulses also results in an enhanced field effect, as seen from increased plasmon response of the metal nanoparticles. Transient absorption measurements confirm the synergy between these two inherently different nanomaterials, causing them to display greater excitation features. Better understanding of metal cluster-metal nanoparticle interactions will have important implications in designing light harvesting systems, and optoelectronic devices.
当分子或团簇靠近金属颗粒时，它们的电子跃迁会显著增强。我们现在已经探究了在较大的（等离子体）金和银纳米颗粒附近，类分子的、谷胱甘肽包覆的金团簇（Au-GSH）的非共振激发。通过单光子激发获得了Au-GSH的激发态吸收光谱。Au-GSH的特征吸收使我们能够探究与团簇耦合的激发等离子体纳米颗粒的影响。尽管红外（775 nm）激光脉冲不会产生Au-GSH*，但当这些团簇与金属（金、银）纳米颗粒耦合时会形成激发态。有趣的是，从金属纳米颗粒等离子体响应的增加可以看出，用775 nm激光脉冲对Au-GSH/AgNP进行耦合激发也会导致场效应增强。瞬态吸收测量证实了这两种本质上不同的纳米材料之间的协同作用，使它们表现出更强的激发特性。更好地理解金属团簇与金属纳米颗粒之间的相互作用将对光收集系统和光电器件的设计具有重要意义。
