子計畫一:密度矩陣方法的研究；子計畫二：圓錐交叉方法的研究；子計畫三：振動鬆弛方法的研究

Abstract

計畫名稱：子計畫一 密度矩陣方法的研究 使用飛秒時間分辨實驗研究超快過程中，時常觀測到quantum beat。因此要 分析所測量的飛秒時間分辨光譜、密度矩陣是最理想的方法。因為它能同時描述 體系的population 和phase (或coherance)的動態。在本計劃我們將發展利用 密度矩陣方法來描述體系的population 及phase 的動態及解析利用飛秒 pump-probe 實驗量測的結果。 ----------------------------------------------------------------------------------------------------------------- 計畫名稱：子計畫二 圓錐交义方法的研究 在這個項目中，ππ*-nπ*吡嗪的無輻射程將作為一個例子來研究圓錐交义的重 要性。2010 年Suzuki 的團隊利用22 飛秒時間分辨的雷射研究吡嗪ππ*態的動 態。在這種情況下，圓錐交义普遍認為這種非絕熱過程中發揮了重要作用，此計 畫將探討如何利用圓錐交义的非絕熱過程及飛秒時間分辨光譜的影響。 ----------------------------------------------------------------------------------------------------------------- 計畫名稱：子計畫三 振動鬆弛方法的研究 另一個重要的超快過程，振動鬆弛此種過程發生在sub-ps 及ps 的時段，從來 没有被詳細研究過。此計畫將著重研究此過程。將選擇水二聚體振動鬆弛為例子 來做計算。振動鬆弛的主要原因是振動模式之間的耦合所造成。

Title：Part I-- Investigations of Density Matrix Method Using femto-second (fs) time-resolved experiments to study ultrafast processes, quantum beat phenomena is often observed. To analyze the fs time-resolved spectra, the density matrix method which can take care of the description of the dynamics of population and coherence of the system is a powerful theoretical technique and will be presented in this project. How to employ it to study the pump-probe experiments and fs ultrafast processes will be described. ----------------------------------------------------------------------------------------------------------------- Title：Part II-- Investigations of Conical Intersection In this project, the ππ*-nπ* transition of pyrazine will be used as an example to demonstrate the application of the density matrix method. Recently, Suzuki’s group have employed the 22 fs time resolution laser to study the dynamics of the ππ* state of pyrazine. In this case, conical intersection is commonly believed to play an important role in this non-adiabatic process. How to treat the effect of conical intersection on non-adiabatic processes and fs time-resolved spectra will be presented. ----------------------------------------------------------------------------------------------------------------- Title：Part III-- Investigations of Vibrational Relaxation Another important ultrafast process, vibrational relaxation which takes place in sub-ps and ps range and has never been carefully studied will be treated in this project. The vibrational relaxation in water dimer will be chosen to demonstrate the calculation. Vibrational relaxation is mainly due to the anharmonic coupling among the vibrational modes.