以表面增強拉曼散射光譜探討影響有機分子於銀表面之吸附行為

SERS Investigation on the Adsorption Behavior of Organic Molecules on Ag Surface

賀俊賢(Chun-Hsien Ho)

指導教授 ： 李世琛

中原大學/理學院/化學研究所/碩士(2013年)

https://doi.org/10.6840/cycu201300552

摘要

本研究探討有機分子(甲基橙與對巰基苯甲酸)吸附於奈米銀的表面增強拉曼散射現象。研究分為兩部份：第一部份是利用氫電漿和氧電漿處理奈米銀的表面性質。研究發現氧電漿處理可以去除表面的有機殘留物質，氫電漿處理可以將表面的氧化物還原。第二部份是藉由改變有機分子的濃度、pH值和添加聚集劑，觀察有機分子的吸附現象。研究發現對巰基苯甲酸在鹼性和中性時，是由羧基吸附於奈米銀基底，但在酸性時，羧基會有質子化現象發生，改由巰基吸附於奈米銀基底。添加聚集劑，有機分子與銀粒子間的吸引力可以增強，也可以改變奈米銀的顆粒大小，造成表面增強拉曼散射效應的增強。我們發現Freundlich和Langmuir兩種吸附等溫線模式可用來解釋改變有機分子的濃度所得到的拉曼強度作圖之趨勢。針對XPS、SEM、GAUSSIAN計算結果與拉曼和吸附等溫線的關聯性，我們將會有詳細的討論。

關鍵字

吸附等溫線 ； 電漿 ； 表面增強拉曼散射

並列摘要

This study investigated the surface-enhanced Raman scattering phenomenon of organic molecules (methyl orange and 4-mercaptobenzoic acid) adsorbed on silver nanoparticles. This study was divided into two parts: the first part was to use hydrogen plasma and oxygen plasma for the treatment of the surface properties of silver nanoparticles. We found that the oxygen plasma treatment can remove the organic residues on the surface; while the hydrogen plasma treatment can make the oxides on the surface be reduction. The second part was to observe the adsorption of organic molecules by changing the organic molecule concentration and pH value, as well as adding aggregating agents. The results showed that 4-mercaptobenzoic acid adsorbs on silver nanoparticles substrate by the carboxyl group in alkaline and neutral conditions. However, in acidic condition, the carboxyl group was protonated and adsorbed by the thiol group on the silver nanoparticles substrate. By adding aggregating agent, the attraction force between the organic molecules and silver particles increased, and silver particle size was changed to enhance the surface-enhanced Raman scattering effect. We found that Freundlich and Langmuir adsorption isotherm models can be used to interpret the trends of Raman intensity versus changing organic molecule concentration. We will discuss the relationship between XPS, SEM, GAUSSIAN calculation results, and Raman and adsorption isotherm curves in detail.

並列關鍵字

adsorption isotherm ； surface-enhanced Raman scattering ； plasma treatment

參考文獻

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