本實驗以晶種介質成長法合成長寬比為2.5、4與5的三種金奈米棒(AuNRs660、AuNRs780與AuNRs870)，經由二次成長將三種金奈米棒變形(AuDBs660、AuDBs780與AuDBs870)，以化學還原法將銀還原其表面形成金銀核殼型奈米粒子並比較不同長寬比對銀殼大小、形狀、截角程度的影響。金奈米棒長寬比的差異性越大，長方體與雙三角錐生長之銀殼才有顯著差異。AuNRs與AuDBs生長銀殼後的UV-Vis吸收光譜之最大吸收峰波長會隨最長軸的增長而紅位移，而銀殼頂點若存在截角則會降低最長軸長度使吸收峰波長藍位移。 室溫包銀以AuNRs870與AuDBs870測試CTAC濃度、鹼性添加劑添加量、AgNO3添加量、反應時間與反應溫度以最佳化反應條件。CTAC同時降低了反應時間與溫度，其氯離子可與銀離子形成AgCl改變銀離子的釋放速率以控制銀還原速率；鹼性添加劑可提高AA反應活性，能藉由鹼性添加劑的添加量間接調控銀離子還原速率；AgNO3添加量直接影響了銀殼包覆完整性與副產物之銀顆粒的數量；反應溫度則影響了截角程度與反應速率。 Gold nanorods (AuNRs) with different aspect ratios (AR) of 2.5, 4 and 5 (AuNRs660, AuNRs780 and AuNRs870) are synthesized by seed-mediated growth method. Gold nanodumbbells (AuDBs) are prepared by the reduction of gold ions in the presence of gold nanorods. Gold nanorods and gold nanodumbbells are employed in the synthesis of gold-silver core-shell nanoparticles (Au@Ag NPs). Adding AgNO3 at 75 ºC, then Ag+ was reduced on the surface of gold nanorods by ascorbic acid. With the increase of the aspect ratios of these good nanorods, we observed red-shift of the longitudinal SPR band. The reaction in hexadecyltrimethyl ammonium chloride (CTAC) solution not only shortens the reaction time but also declines the reaction temperature to room temperature. We control the concentration of CTAC, the addition of sodium hydroxide (NaOH), silver nitrate (AgNO3), reaction time and reaction temperature to optimize the reaction conditions. The addition of AgNO3 affects the integrity of silver shells and the number of the silver particles as side-products directly. The reactivity of ascorbic acid (AA) could be enhanced with the increase in amount of hydroxide, and the addition of NaOH would further affect the reduction rate of Ag+.
