| 摘要: | 首先本研究以聚4乙烯吡啶(poly(4-vinylpyridine), P4VP)經熱燒結後製備出富含氮碳材，將其應用於作為表面拉曼光譜訊號增強(surface-enhanced Raman scattering, SERS)基材後，觀察到其增強訊號的能力良好。探討聚4乙烯吡啶經一系列熱燒結溫度下製備樣品的氮摻雜組態後，發現氮組態中的四級氮(graphitic-N)比例隨燒結溫度升高而增加，此時最高占據分子軌域和最低未占據分子軌域間能隙(HOMO-LUMO gap)降低，電荷傳遞能力(charge transfer)提升，同時四級氮周圍的碳上有很高的區域電子雲密度(charge density)使富含氮碳材帶有更高的極性，則富含氮碳材與分子間的偶極-偶極力(dipole-dipole interaction)也會提升，最終作為表面拉曼光譜訊號增強基材的能力也跟著提升。
接下來由於聚4乙烯吡啶(P4VP)的熱燒結溫度已達臨界點，利用前驅物降低聚4乙烯吡啶(P4VP)熱穩定性，即以金屬為前驅物製備高分子薄膜後，經熱燒結製備一系列金屬摻雜富含氮碳材。期望藉由金屬離子摻雜，製備出具金屬與氮鍵結的拉曼光譜訊號增強能力的基材。藉由Near Edge Absorption X-ray Fine Structure(NEAXFS)觀察後，發現金屬摻雜後改變氮元素組態而且最高佔據分子軌域與最低未佔據分子軌域間能隙(HOMO-LUMO gap)降低，電荷傳遞能力(charge transfer)提升，最終得到具有明顯表面拉曼光譜訊號提升的金屬摻雜富含氮碳材，以金屬為前驅物製備之富含氮碳材的表面拉曼光譜訊號能力相較於原先的富含氮碳材之效果提升許多。
最後探討鹵素摻雜於富含氮碳材後提升表面拉曼光譜訊號增強能力的可能性。以聚4乙烯吡啶(poly(4-vinylpyridine), P4VP)製備高分子薄膜後，於鹵素摻雜後經熱燒結製備鹵素摻雜富含氮碳材。發現到鹵素離子摻雜後形成鹵素與氮鍵結使周圍碳材帶有更強的正電荷密度而更容易吸引電子而提升電荷傳遞能力，同時鹵素離子的極性也提升了分子與基材間的偶極-偶極力，使表面拉曼光譜訊號增強能力更好。而於熱燒結前進行鹵素摻雜，除了鹵素離子的貢獻外，鹵素摻雜後的樣品熱裂解溫度下降而導致在相同溫度下燒結時，碳化程度較未摻雜的樣品提升也是使表面拉曼光譜訊號增強能力更好的原因之一。
;Nitrogen-enriched carbon materials could be fabricated by thermal pyrolysis of poly(4-vinylpyridine) thin film. By using the nitrogen-enriched carbon materials as surface-enhanced Raman scattering substrates, the excellent enhancement of Raman signal is observed. From the analysis of nitrogen configurations for nitrogen species for nitrogen-enriched carbon materials, the proportion of graphitic-N depends on pyrolysis temperature. Due to the fact that the presence of graphitic-N could reduce the band gap, graphitic-N could favor charge transfer between the substrate and the molecule. Due to different electronegativity between carbon and nitrogen, positive high charge densities could be present on the carbons neighboring to graphitic-N, which may result in dipole-dipole interactions between the substrate and the molecule. As a result, the ability of surface-enhanced Raman scattering substrate can be finely determined by pyrolysis temperature.
In order to improve the ability of surface enhance Raman scattering, we use the metal as precursor to fabricate nitrogen-enriched carbon nanosheets through thermal pyrolysis of homopolymer poly(4-vinylpyridine). With Near Edge Absorption X-ray Fine Structure (NEAXFS) characterization for nitrogen-enriched carbon nanosheets, the configurations of nitrogen within nitrogen-enriched carbon nanomaterials are changed. As a result, graphitic-N and metal-N promote the better ability of surface-enhanced Raman scattering.
In the last part, halogen doping was applied to improve the ability of surface-enhanced Raman scattering substrate. Halogen doping was first imposed on P4VP homopolymers and then thermal pyrolysis was carried out. We successfully fabricate halogen-doped within nitrogen enriched carbon nanosheets, which show improved Raman scattering intensity enhancement. From the analysis of nitrogen configurations, halogen-nitrogen bonds were found. The halogen-nitrogen bonds could induce more positive charges on carbons that promote the charge transfer ability between substrate and molecule. The polarity of halogen promotes dipole-dipole interactions between substrate and molecule. As a result, halogen doping indeed improves the ability of surface-enhanced Raman scattering substrate. Additionally, carbonization could generate nanosheets with high crystallinity. As a result, such carbon nanosheets show improvement of Raman scattering intensity of adsorbed dye molecules. |
