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Please use this identifier to cite or link to this item:
https://tkuir.lib.tku.edu.tw/dspace/handle/987654321/32762
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| Title: | InN吸附於Rutile TiO2(110)表面的電子性質理論研究與CH3NH2在Si(100)表面解離吸附反應及分子動態模擬IR光譜 |
| Other Titles: | Theoretical studies for electronic properties of InN adsorption on Rutile TiO2(110) surface & Dissociative adsorption of CH3NH2 on Si(100)surface and molecular dynamic simulated IR spectra |
| Authors: | 張耕嘉;Jang, Gung-jya |
| Contributors: | 淡江大學化學學系碩士班
林志興;Lin, Jyh-shing |
| Keywords: | 分子動態模擬;解離吸附反應;電子性質;光譜;IR spectra;molecular dynamic;Si(100) surface;Rutile TiO2 |
| Date: | 2009 |
| Issue Date: | 2010-01-11 02:42:54 (UTC+8) |
| Abstract: | 本論文分為兩部份，第一部份中我們使用密度泛函理論計算軟體CASTEP搭配 GGA 層級的交換相關泛函、ultra-soft 方案之虛位勢及平面波基底來計算InN(氮化銦)吸附在Rutile TiO2(110)-1x1與2x1表面後的電子性質並與過去InN吸附在Anatase TiO2(101)表面的結果做比較。結果顯示出當InN以1.0ML覆蓋率吸附在2x1表面上時，
其結構與吸附能雖與1x1 表面的計算結果有些差距，但其電子性質
(能隙、態密度分佈)皆顯示出 InN- Rutile TiO2(110)的組合並不適合作為染料敏化太陽能電池中將可見光能吸收並將InN上基態電子激發並注入至TiO2內之機制發生的平台。另外從不同覆蓋率的計算結果也能得到相同的結論。上述現象是因為在吸附之前Anatase(101)表面即有明顯且與InN類似的軌域分佈，這使得吸附後系統呈現出來的態密度分佈相當適合電子在InN與TiO2之間的傳遞;反之Rutile(110)表面本身的軌域分佈並不明顯，所以在吸附後的態密度分佈並不適合前述傳遞機制進行。
在第二部份則使用密度泛函理論計算軟體SIESTA搭配GGA層級的交換相關泛函、Troullier-Martin方案之虛位勢及AO 基底來探討NH2CH3在 Si(100)表面上的解離吸附反應與分子動態模擬光譜。根據計算結果，NH2CH3會傾向於解離吸附在同一個 Si=Si dimer上，因為同樣在過渡態時，one-dimer途徑中的 N-H鍵斷裂程度比cross-dimer途徑來得小，所以付出的活化能較低。從模擬光譜的計算結果中我們發現其與實驗光譜有相當好的相似性，並且也發現Si-H鍵的振動模式會受到NHCH3官能基在Si 表面上運動所影響而呈現不同的振動頻率。而改變表面大小與溫度所得到的光譜也顯示出若我們在計算中考慮進表面運動與溫度效應，最後得到的光譜確實會更為接近實驗結果。
In section I, DFT based calculation package(CATEP),GGA level exchange-correlation functional, ultra-soft pseudopotential, and plane-wave basis set were used to study the electronic properties of InN adsorbed Rutile TiO2(110)-1x1 and 2x1 surfaces. Our results showed that although changes of surface size and adsorption coverage might result in differences of adsorption structure and Eads, but the analysis of density of states indicates that the combination of InN and Rutile TiO2(110) is not propriate for the electron-injection process form InN to TiO2. By comparing with the results of InN-Anatase TiO2(101) systems, we found that the lack of overlap of orbital density between InN and TiO2 is the reason why InN-Rutile TiO2(101) composites are not siut for electron transfer from InN into TiO2, i.e., the orbital density populations of Rutile TiO2(110) and Anatse TiO2(101) would take control of the electronic properties of InN-TiO2.
In section II, DFT in connection with GGA level exchange-correlation functional, pseudopotential of Troullier-Martin scheme, and
AO basis set were used to study the dissociation reaction of NH2CH3 molecule on Si(100)-4x4 surface. According to the result, instead of cross-dimer pathway, NH2CH3 would dissociate through one-dimer pathway after adsorbsion on Si(100) which has lower activation barrier. Our MD simulated IR spectra showed good similarity with the experimental results. Also, we found that the stretching motion of Si-H bond might be afftect by the NHCH3 fragment on Si(100) surface and leads to different absorbsion frequencies. Finally, from the simulated spectra of Si(100) surface in smaller size and of those under low
temperature, we know that by considering the surface motion effect from Si(100) surface and the temperature effect we can obtain simulated spectra closer to the experimental results. |
| Appears in Collections: | [Graduate Institute & Department of Chemistry] Thesis
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