多原子體系的化學反應動力學研究

張東輝++戴東旭++謝代前++邊文生

摘 要：利用自主研發(fā)的窄線寬OPO激光和受激Raman技術首次在交叉分子束中實現(xiàn)了對氫氣振動激發(fā)態(tài)的研究，并在F+HD（v=1）→HF+D反應中觀察到只能通過反應物振動激發(fā)得以探測的反應共振態(tài)，極大地提高了對反應共振態(tài)的認識。通過實驗與理論對F+CHD3反應中CH振動激發(fā)對反應的影響進行研究，在實驗上發(fā)現(xiàn)了CH振動激發(fā)會導致處于某些振轉(zhuǎn)態(tài)反應產(chǎn)物的輕度減少，與劉國平等人在Science上所報導的大大抑制該反應有著明顯的差異。更有意思的是我們理論研究發(fā)現(xiàn)總的來說CH振動激發(fā)能促進該反應的進行，而實驗所發(fā)現(xiàn)的抑制作用是由于所測量產(chǎn)物的局限性所引起的。另外，還在SO2光化學動力學中發(fā)現(xiàn)了振動激發(fā)對其反常同位素效應的影響，研究了HOD振動激發(fā)對其在Cu（111）面解離吸附的影響。在理論方法發(fā)展方面，發(fā)展了一種新的減維模型，使在態(tài)-態(tài)水平研究X+YCZ3→XY+CZ3類型的反應成為可能，通過對J=0情況下H+CH4反應的計算發(fā)現(xiàn)該模型有很高的精度。利用該模型，我們計算得到了H+CD4反應的微分截面，與實驗取得了高度吻合，表明已能較為精確地計算多原子反應的態(tài)-態(tài)微分截面。

關鍵詞：多原子分子體系 化學反應動力學 振動激發(fā)態(tài) 非絕熱量子動力學方法

The Annual Report of The Chemical Reaction Dynamics Study on the Polyatomic System

Zhang Donghui2 Dai Dongxu1 Xie Daiqian2 Bian Wensheng3

（1.Dalian Institute of Chemical Physics， Chinese Academy of Sciences； 2.Nanjing University； 3.Institute of Chemistry， Chinese Academy of Sciences）

Abstract：In the past year， under the support of the 973 program we have made significant progress on studying the effects of reagent vibrational excitation of reaction dynamics. With the state-of-the-art high-power nanosecond OPO laser developed in our lab， we successfully carried out a crossed-molecular beam experiment on vibrationally excited hydrogen molecule for the first time using the stimulated Raman process. In the F+HD（v=1）→HF+D reaction， we observed dynamical resonances which is only accessible by reagent vibrational excitation， substantially advanced our understanding on dynamical resonance in chemical reactions. We also carried out a joint experimental and theoretical study on the effects of CH stretching excitation on the F+CHD3 reaction. Experimentally， we found that CH stretching excitation only leads to slight reduction of reactivity of the reaction for some detected product states， very different from what was reported by Liu and coworkers on Science. However， our theoretical study revealed that CH excitation actually prompts the reaction and the reduction of reactivity observed by experiment is caused by limited measurements on the product states. In addition， we uncovered the Vibronic original of the sulfur mass-independent isotope effects in photoexcitation of SO2， studied the effects on HOD vibrational excitation on the chemisorption of the molecule on Cu（111） surface. On the theory side， we developed a new reduced-dimensionality model to calculate state-to-state differential cross section for the X+YCZ3→XY+CZ3 type of reactions， which was found to have a qualitative level of accuracy for the H+CH4 reaction with J=0. Using the new mode， we computed differential cross sections for the H+CD4 reaction. Excellent agreement was achieved between theory and experiment， indicating we are able to calculate accurate state-to-state differential cross section of this type of polyatomic reactions. We published more than 24 SCI papers， including one in Science， one in PNAS.

Key Words：Polyatomic system； Reaction dynamics； Vibrationally excited state； Nonadiabatic quantum dynamics