理學院: 化學研究所指導教授: 李遠哲; 倪其焜李勤Lee, ChinChinLee2017-03-022018-07-102017-03-022018-07-102016http://ntur.lib.ntu.edu.tw//handle/246246/272014苯酚在紫外光區域的主要光解反應是氫原子分解，本實驗探討265~275 nm光解能量下該通道的分解途徑，並使用118 nm雷射作游離檢測。利用實驗室所架設的多重質量離子影像質譜儀，可以清楚分辨分解產生斷鍵(Dissociation)、熱分子的斷鍵離子化(Dissociative Ionization)與斷片的斷鍵離子化(Dissociative Ionization of Fragment)等三種不同的分解途徑，三種通道的代表斷片分別為C6H5O(m/z 93)、C5H6(m/z 66)和C5H5 (m/z 65)，C6H5O是苯酚掉一個氫，C5H6來自熱苯酚的裂解(Craking)，而C5H5是來自C6H5O的裂解。本實驗利用C6H5O與C5H5的訊號，將苯酚氫原子分解通道的移動動能分布計算出來，發現有一慢一快的兩個峰，位置落在2000和7000 cm-1附近，前者是具有高振動能的苯酚自基態的分解，後者來自苯酚激發態的分解。最後，配合苯酚高振動動能基態(Highly vibrational excited phenol in the electronic ground state)的生命週期量測，得到光解波長為269.291、275.113 nm產生的熱苯酚週期為96、62 μs，證明傳統使用遲滯時間(Delay Time)僅幾奈秒的實驗技術得到的結果，應看不到來自苯酚高振動動能基態的分解。 此外，本實驗亦針對苯酚在193 nm光解下是否有C6H5O第一激發態做研究。實驗結果看不到第一激發態的訊號，我們推論在193 nm光解下可能沒有C6H5O第一激發態生成，或者C6H5O第一激發態的生命週期太短無法在本系統中被偵測到。The major photodissociation channel of phenol in UV region in gas phase is OH bond fission. In this work, we focus on the photolysis wavelength around 265~275 nm with ionization wavelength at 118 nm. By the advantage of our homemade multi-mass system, it is easy to tell the difference between dissociation, dissociative ionization of hot molecule, and dissociative ionization of fragment. In phenol photodissociation results, these three channels are founded by fragments C6H5O (m/z 93), C5H6 (m/z 66), and C5H5 (m/z 65). Fragments C6H5O are from hydrogen elimination of phenol. Fragments C5H6 and C5H5 are from dissociative ionization of hot phenol and fragments C6H5O. We use fragments C6H5O and C5H5, which is from C6H5O, to calculate the total kinetic energy release of hydrogen elimination channel, and found that it is bimodal. The slow peak is located at 2000 cm-1 and is from the dissociation of highly vibrational phenol ground state. The fast peak is around 7000 cm-1 and is determined from phenol excited state dissociation. The lifetimes of phenol under photolysis wavelength 269.291 and 275.113 nm are about 96 and 62 μs, respectively, which are much longer than the pump-probe delay time of traditional potodissociation technique. In this study, we prove that it is impossible to detect dissociation channel from such long lifetime of highly vibrational phenol ground state by using traditional technique. We also try to figure out whether the excited A ̃ state phenoxyl radical is produced or not. According to our results, we did not detect the signal of A ̃ state phenoxyl radical. This may due to two possible reasons. First, A ̃ state phenoxyl radical is not generated under photodissociation at 193 nm. Second, the lifetime of A ̃ state phenoxyl radical is too short to be detected in our system.2945459 bytesapplication/pdf論文公開時間: 2016/9/13論文使用權限: 同意有償授權(權利金給回饋學校)苯酚光分解化學動力學質譜PhenolPhotodissociationChemical DynamicsMass Spectroscopythesis10.6342/NTU201601790http://ntur.lib.ntu.edu.tw/bitstream/246246/272014/1/ntu-105-R03223160-1.pdf