鋪陳在其他金屬上及覆蓋在其他金屬下銀奈米顆粒的侷域表面電漿子共振行為

Localized Surface Plasmon Resonance Behaviors of Silver Nanoparticles Overlaid on and Covered by Other Metals

蔡宇軒(Yu-Hsuan Tsai)

指導教授 ： 楊志忠

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201902280

摘要

本論文研究中，我們在銀奈米顆粒周遭設置各種金屬，包含其下之間置層以及其上之覆蓋層，並量測樣品穿透頻譜以檢視銀奈米顆粒所產生侷域表面電漿子共振行為的變化。間置層和覆蓋層金屬包括鈦、鋁、鎳、金、鉑，我們也使用包括氮化矽及二氧化矽的介電材質，同時也變化各層厚度以為比較。隨著材料變化，侷域表面電漿子共振波長產生紅移、藍移或甚至消失。理論上，金屬的間置層會使得銀奈米顆粒的表面電漿子之基板模態共振行為消失；覆蓋層則會使銀奈米顆粒的表面電漿子之空氣模態共振行為消失。然而實驗顯示出不同於理論之結果，不同金屬界面電子濃度產生變化而影響介電常數，使得金屬界面兩側的介電常數之實數部分一邊為正數，一邊為負數，滿足了在界面產生表面電漿子共振的條件，因此我們可以觀測到銀奈米顆粒的侷域表面電漿子共振行為。

關鍵字

表面電漿子共振 ； 侷域表面電漿子共振 ； 銀奈米顆粒

並列摘要

The transmission spectra of various structures surrounding Ag nanoparticles (NPs) are measured to show the transmission depressions or localized surface plasmon (LSP) resonance features of the Ag NPs. The structures surrounding Ag NPs include the interlayers and coverages of various metals different from Ag, such as Ti, Al, Ni, Au, and Pt, with different thicknesses. For comparison, dielectrics of SiN and SiO2 are also used as interlayer and coverage materials. The blue or red shift, or even disappearance of the LSP resonance feature indicates the different surface plasmon (SP) resonance behaviors at the interfaces between Ag and other metals or dielectrics. Theoretically, a metal interlayer and a metal coverage should lead to the disappearances of the substrate and air LSP modes, respectively. However, the persistence of the LSP resonance feature in the experimental observation indicates that the metal contact causes the modification of metal dielectric constants (DCs) near the interface. The modification of DC can result in a positive DC real part in one of the contacting metal and a negative DC real part in another metal near the interface such that SP resonance can occur at the metal/metal interface.

並列關鍵字

SP resonance ； LSP ； Ag nanoparticles

參考文獻

1. S. Nie and S. R. Emory, “Probing Single Molecules and Single Nanoparticles by Surface-enhanced Raman Scattering,” Science 275(5303), 1102-1106 (1997).

2. A. Tao, F. Kim, C. Hess, J. Goldberger, R. He, Y. Sun, Y. Xia, and P. Yang, “Langmuir-Blodgett Silver Nanowire Monolayers for Molecular Sensing Using Surface-enhanced Raman Spectroscopy,” Nano Lett. 3(9), 1229-1233 (2003).

3. J. Homola, S. S. Yee, and G. Gauglitz, “Surface Plasmon Resonance Sensors: Review.” Sensors and Actuators B 54(1-2), 3-15 (1999).

4. A. J. Haes, W. P. Hall, L. Chang, W. L. Klein, and R. P. Van Duyne, “A Localized Surface Plasmon Resonance Biosensor:  First Steps toward an Assay for Alzheimer's Disease,” Nano Lett. 4(6), 1029-1034 (2004).

5. X. Huang, I. H. El-Sayed, W. Qian, and M. A. El-Sayed, “Cancer Cell Imaging and Photothermal Therapy in the Near-infrared Region by Using Gold Nanorods,” J. Am. Chem. Soc. 128(6), 2115-2120 (2006).