金奈米棒SPR在有機溶劑中的化學位移偵測及金與硫化鎘包覆結構中SPR引發螢光增強之探討

Spectral-Shift Detection of Organic Solvents with Plasma Resonance of Gold Nanorods and Surface Plasmon Induced Photoluminescence Enhancement on Au@CdS Core-Shell Nanostructure

吳仁家(Jen-Chia Wu)

指導教授 ： 陳家俊

國立臺灣師範大學/理學院/化學系/碩士(2004年)

摘要

摘 要
PARTⅠ
就我們所知的文獻當中，我們在研究中發現的金奈米棒在不同的有機溶劑中的表面電漿共振吸收變化，是首度在實驗中被觀察到。我們成功利用簡單的靜電作用，將水相的金奈米棒相轉移到有機相當中。並且在研究當中我們發現金奈米棒的長軸最大吸收波長，隨不同有機溶液的折射率的改變呈線性關係，此結果與我們所提出的理論是吻合的。這樣的結果表示出，金奈米棒可被用來作為環境介質介電常數偵測的新型感測材料。
PARTⅡ
我們成功合成出Au@CdS殼層包覆結構。在吸收光譜及螢光光譜的測量中，我們可看到金奈米粒子與硫化鎘的特性吸收及放光光譜，並且透過分析式電子顯微鏡的元素分析與結構鑑定得以確定其殼層結構與組成成分。這樣的包覆結構合成主要是在探討，金奈米粒子表面電漿共振效應引發的光學增強效應。實驗中，比較Au@CdS殼層包覆結構與CdS的螢光光譜，發現Au@CdS殼層包覆結構有較強的放光。此可能是因為金的表面電漿共振帶與CdS放光位置靠近，造成CdS放光的增強。此外，亦有可能是金奈米粒子表面電漿共振使CdS電子電洞的結合率變快，造成螢光上的增強。

關鍵字

金 ； 表面電漿共振 ； 硫化鎘

並列摘要

Abstract
PARTⅠ
We have reported the first observation, to our knowledge, of localized plasmon resonance of gold nanorods in different solvents. In the experiments,we have successfully transfered gold nanorods from aqueous solutions into usual organic media by the use of the static electric interaction.The experimental data show a simple relation existing between the longitudinal SPR wavelength and the refractive index of the solvent, which is consistent with the theoretical predication. This result indicates that gold nanorods can be used as a novel sensitive detector to extract the optical properties of surrounding dielectric media if the aspect ratio and the ligand shell thickness are known.
PARTⅡ
In our studies,we have successfully synthesized the Au@CdS core-shell nanocrystals. UV-Vis absorption and fluorescence spectra were measured to gain an insight into the optical properties of the Au@CdS core@shell nanocrystals.The spectra showed the results similar to the typical UV-Vis absorption and fluorescence spectra of gold and CdS nanocrystals. Analytical transmission electron microscopy (AEM) was used in conjunction with energy dispersive spectroscopy (EDS) to verify the core-shell compositions and the structure.The Au@CdS core-shell structure was synthesized to realize the effect of surface plasmon induced optical enhancement. In the experiments,compared to the CdS nanoparticles, the Au@CdS core-shell nanostructure exhibited much stronger and sharper blue and red emissions. In our opinions,the enhancement of PL emission presumably results from the energy transfer from the collection of electrons around the Au particles surface to the neighboring CdS nanocrystals.Otherwise,SPR may also cause the increase of the electron-hole recombination rate in the CdS thus enhancing the emission intensity.

並列關鍵字

gold ； SPR ； CdS