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Title: | 掃描穿隧顯微術研究Cu(111)單晶表面之鐵-苝四甲酸二酐(Fe-PTCDA)的排列與電子結構 Monolayer Structure and Electronic Properties of Fe-Perylenetetracarboxylic-dianhydride (Fe-PTCDA) on Cu(111) |
Authors: | Hsu-Han Tsai 蔡旭涵 |
Advisor: | 陳俊顯(Chun-hsien Chen) |
Keyword: | 掃描穿隧顯微術,掃描穿隧能譜,Cu(111),?四甲酸二酐,金屬-有機錯合物,電荷轉移, Scanning Tunneling Microscopy,Scanning Tunneling Spectroscopy,Cu(111),PTCDA,Metal-organic Complex,Charge Transfer, |
Publication Year : | 2014 |
Degree: | 碩士 |
Abstract: | 本論文研究 Cu(111)單晶表面的苝四甲酸二酐(PTCDA)與鐵-苝四甲酸二酐
(Fe-PTCDA)兩種單層分子膜的排列與電子結構。Fe-PTCDA 錯合物的排列結構由 掃描穿隧顯微術(STM)加以分析;PTCDA 和Fe-PTCDA 的電子結構以掃描穿隧能 譜(STS)進行量測。 在研究初期,儀器並未順利運作,無法在標準試片(HOPG)表面上得到原子級 解析度,也未能進行掃描穿隧能譜實驗。藉由最佳化濺射探針的參數以改善探針的 品質、改善腔體的真空度、改善儀器接地和微調防震桌水平度等方式,方得以經常 地獲得HOPG 原子級解析度之影像,並以此為標準校正STM 的壓電驅動器。在安 裝並設定鎖相放大器之後,先後以HOPG、Cu(111)和Ag(111)表面測試,可成功地 獲得dI/dV 能譜和駐波的dI/dV 圖。 實驗方法為先準備Cu(111)單晶表面;經由熱阻式蒸鍍獲得PTCDA/Cu(111)樣 品;或是同時蒸鍍鐵和PTCDA 分子,再經最後加熱而得Fe-PTCDA/Cu(111)樣品。 dI/dV 能譜顯示PTCDA 的最低未占軌域(LUMO)與Cu(111)形成混成態,STM 影像 亦確認此結果。STM 影像顯示Fe-PTCDA 在Cu(111)表面係由兩種位向分子(鏈型 和桄型)構成梯狀排列,且兩種分子的占有態能階相同;從dI/dV 能譜進一步獲知 此占有態能階是由Fe-PTCDA 的LUMO 與Cu(111)所形成之混成態。dI/dV 能譜同 時顯示桄型分子在未占有態具有較鏈型分子高的能態密度,代表鏈型PTCDA 的 LUMO 被鐵原子提供的電子完全占有而桄型PTCDA 的LUMO 僅被部分占有。由 於鏈型分子與4 個鐵原子配位,而桄型分子僅配位2 個鐵原子,可知鐵與PTCDA 間的電荷轉移與配位數有關。 This thesis presents the investigation of PTCDA (3,4,9,10-perylenetetracarboxylicdianhydride) and Fe-PTCDA complex on Cu(111). Monolayer structure of Fe-PTCDA was studied by scanning tunneling microscopy (STM); electronic properties of PTCDA and Fe-PTCDA were measured by scanning tunneling spectroscopy (STS). dI/dV spectra of PTCDA on Cu(111) revealed the formation of a hybrid state, indicative of a strong chemical interaction between the adsorbate and substrate. The molecular orbital involved in the hybridization was LUMO (lowest unoccupied molecular orbital), confirmed by topographic images. Topographic images of Fe-PTCDA/Cu(111) revealed a ladder-like structure, which is distinctly different from the herringbone structure of PTCDA/Cu(111). Two types of molecules were named according to their orientation in a ladder-like structure, that is, chain- and rung-PTCDA. Topographic features of chain- and rung-PTCDA resolved at the molecular level are unprecedented. The images unraveled that both types of molecules had the same occupied molecular state. However, dI/dV spectra showed that rung-PTCDA have higher density of unoccupied states compared with chain-PTCDA. This means that the LUMO of rung-PTCDA is only partially occupied with the electrons donated by Fe. Since chain-PTCDA binds to 4 Fe atoms while rung-PTCDA binds to only 2 Fe atoms, the result showed that the charge transfer from Fe to PTCDA is coordination number-related. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/5220 |
Fulltext Rights: | 同意授權(全球公開) |
Appears in Collections: | 化學系 |
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