論文摘要 利用真空蒸鍍法製作銀奈米微粒，製作出的銀奈米微粒平均粒徑大小為25nm，改變蒸鍍時間可以獲得厚度不同的銀微粒薄膜，用以探討其光學性質及對紫晶分子表面強化拉曼散射(SERS)效應。 銀奈米微粒的吸收光譜顯示採用紫外激發光為激發局部性表面電漿最好的波段，該結論與Mie theory計算相互符合。 銀微粒薄膜的光透射與光反射實驗顯示電磁波在微粒薄膜介質中傳遞其強度隨穿透深度成指數衰減，該現象與在島膜介質中的傳遞相似，在微粒薄膜厚度為4μm時透射光與反射光強度已完全消逝。表面強化拉曼散射(SERS)顯示銀奈米微粒可強化分子震盪訊號，Ag2WO4與紫晶分子的SERS訊號強度在薄膜厚度4μm有一強度轉折點，微粒薄膜厚度小於4μm，SERS強度與微粒數目的增多成正比；厚度超過4μm，SERS訊號開始減弱。銀微粒薄膜退火至島膜型態時，SERS訊號已減弱百分之九十以上，本實驗設定的強化機制主要稱為為激發銀奈米微粒的局部型表面電漿。 低溫強化拉曼散射訊號強度有增強趨勢，在77K時SERS強度比室溫增加百分之三十，其機制應以較多的相關實驗進一步探討。 Abstract Sliver nanoparticles have been broadly used as SERS excitation media. In this studies, Ag nanoparticle filmspace(AGNF) were prepared by the standard thermal evaporation method, and the mean particle diameter was determined by X-ray diffraction and AFM, to be at 25nm. The optical properties and the SERS behavior of the resultant AGNF were investigated. The absorption spectra show that the most efficient band for exciting SPR in Ag nanoparticle lies in the UV regime, which agrees with the predicted result according to Mie theory. The penetrated intensity was found to be exponentially decreasing with the increasing of film thickness. The strongest integrated SERS intensity occurred at a film thickness of 4μm. Annealing of the AGNF results in a dramatic decrease in the SERS intensity, while a 30% increase in the SERS intensity was found when the temperature was cooling to 77K.
