微採樣技術結合表面增強拉曼光譜法在藝術品分析上的應用

Abstract

利用棉紙的微採樣技術非常適用於紙張或書籍上顏料的極微量採集。但是若將奈米銀溶液直接加到微採樣過後的棉紙上，分析物會被溶液沖走，導致難以表面增強拉曼法進行測量。本研究將微採樣過後的棉紙條浸泡在奈米銀溶液中，利用棉紙纖維的毛細現象，成功的將奈米銀顆粒從溶液中分離出來，並且自然附著在分析物上。此方法不僅能夠將乾燥的奈米銀顆粒附著在分析物上，還可以有效降低溶液的背景螢光干擾，因此能夠大幅增強分析物的表面增強拉曼光的強度。以濃度10-6 M的孔雀石綠草酸鹽為例，增強因子可高達2585.6%。為了觀察奈米銀顆粒的動態行為，本研究使用了動態光散射粒徑分析儀和高解析掃描式電子顯微鏡，分別對溶液中的奈米銀及棉紙表面乾燥的奈米銀顆粒，進行了粒徑分布範圍的測量。結果發現，前者的粒徑分布範圍為18.1±12.3 nm，後者的分布範圍則為29.6±20.3 nm，且形狀為球形。這樣的粒徑範圍非常符合表面增強拉曼光的實驗條件。為了確認奈米銀顆粒可被有效隨著毛細現象而從溶液中單離出來，本研究還使用了高解析掃描式電子顯微鏡/能量散射X射線光譜儀，由光譜圖及元素組成比例圖，確認在高解析掃描式電子顯微鏡下觀察到的顆粒確實是銀。最後，本研究開發的微採樣技術結合毛細分離乾燥奈米銀的表面增強拉曼光譜法，成功的應用在油畫微採樣顏料成分的分析。根據分析鑑定結果顯示，在師大典藏品劉自明先生畫作上的微採樣藍色顏料（重量小於~0.0003克），確定為酞青藍。A novel extraction and accumulation method for Ag nanoparticles, utilizing capillary action through a piece of triangular-shaped cotton paper, was demonstrated. This method proves to be highly beneficial for integrating SERS and the BPG Spot Tests, typically employed for examining pigments on paper or in books. In order to investigate the enhancement factor when SERS was applied, malachite green oxalate was selected as the model sample. The dynamic behavior of Ag nanoparticles was also studied.Since the cotton paper had been pre-treated with malachite green oxalate, the extraction and accumulation of Ag nanoparticles on the triangular top led to a dramatic SERS improvement. When malachite green oxalate (at a concentration of 10-6 M) was applied using this method, a remarkable enhancement factor of approximately 3000% was obtained. Finally, the method developed in this study was successfully applied to the analysis of pigments in paintings belonging to the university collection. The findings reveal that phthalocyanine blue was a popular pigment used in paintings during the 1950s decade.