林聖賢臺灣大學：化學研究所許峰誠Hsu, Feng-ChengFeng-ChengHsu2007-11-262018-07-102007-11-262018-07-102006http://ntur.lib.ntu.edu.tw//handle/246246/51654在本篇論文中，我們利用超快雷射光譜技術研究對-二苯乙烯基苯的三種異構物（順順-，順反-，反反-對-二苯乙烯基苯）順-反異構化的機制。我們建立了一套異波長激發探測吸收光譜技術來量測各種異構物在激發態之等方向性及非等方向性的瞬時行為。我們也量測這三種異構物在激發態的瞬時光譜。藉由分析等方向性的瞬時行為及瞬時光譜的演變過程，我們得知各異構物分子在激發態的能量弛豫及順-反異構化的過程。而非等方向性瞬時行為的研究提供在順-反異構化過程中分子結構變化的證據。最後，我們提出一套完整的動力學模型來描述對-二苯乙烯基苯的順-反異構化的特徵及其異構化的速率。In this thesis, we report the ultrafast spectroscopic studies of cis/trans photo- isomerization for three 1,4-distyrylbenzene (DSB) isomers: trans,trans-DSB, cis,trans-DSB, and cis,cis-DSB. A two-color pump-probe transient absorption setup was built to investigate their isotropic and anisotropic transient behaviors simultaneously, as well as the temporal evolution of their excited-state spectra. The population relaxation dynamics and cis/trans photoisomerization process were carefully examined by the isotropic transient study. The transient anisotropy study provided evidences of molecular structures during the photoisomerization process. Finally, a comprehensive model was proposed to elucidate the main characteristics and essential time constants of the cis/trans photoisomerization processes among the three 1,4-distyrylbenzene isomers.Acknowledgement i Abstract ii Table of Contents iv List of Figures vii List of Tables x Chapter 1 Introduction 1 1.1 Cis/trans photoisomerization of stilbene 3 1.2 Photophysics and photochemistry of 1,4-distyrylbenzene 5 1.3 Ultrafast pump-probe spectroscopy 6 References 10 Chapter 2 Experiments 14 2.1 Sample preparation 14 2.2 Steady-state spectroscopic measurements 15 2.2.1 Absorption and fluorescence 15 2.2.2 Fluorescence lifetime and quantum yield 16 2.2.3 Photoisomerization kinetics 18 2.3 Time-resolved spectroscopic measurements 18 2.3.1 Femtosecond laser system 18 2.3.2 Optical parametric amplifier and supercontinuum generator 19 2.3.3 Two-color pump-probe setup 22 2.3.4 Acquisition of transient absorption signal 25 2.3.5 Acquisition of time-sliced transient absorption spectrum 29 Appendix 2A Fluorescence lifetime measurements with phase modulation method 30 Appendix 2B Determining quantum yield with integrating sphere method 31 References 35 Chapter 3 Results and Discussion 36 3.1 Basic photophysical properties of 1,4-distyrylbenzene 36 3.1.1 Absorption and fluorescence 36 3.1.2 Photoisomerization kinetics 39 3.2 Instrument response of time-resolved measurements 41 3.3 Trans,trans-1,4-distyrylbenzene 45 3.3.1 Transient absorption study 45 3.3.2 Excitation energy dependence 53 3.3.3 Transient anisotropy 58 3.4 Cis,trans-1,4-distyrylbenzene 65 3.4.1 Transient absorption study 65 3.4.2 Transient anisotropy 74 3.5 Cis,cis-1,4-distyrylbenzene 78 3.5.1 Transient absorption study 78 3.5.2 Transient anisotropy 84 3.6 Photoisomerization of 1,4-distyrylbenzenes 87 Appendix 3A Convolution of molecular response with Gaussian instrument response 91 Appendix 3B Isotropic and anisotropic molecular response 93 References 97 Chapter 4 Conclusions 996087765 bytesapplication/pdfen-US超快光譜學順反異構化對-二苯乙烯基苯1,2-二酚基乙烯ultrafast spectroscopyphotoisomerization1,4-distyrylbenzenestilbenethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/51654/1/ntu-95-F87223033-1.pdf