多原子體系的化學(xué)反應(yīng)動(dòng)力學(xué)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(shù)首次在交叉分子束中實(shí)現(xiàn)了對(duì)氫氣振動(dòng)激發(fā)態(tài)的研究，并在F+HD（v=1）→HF+D反應(yīng)中觀察到只能通過反應(yīng)物振動(dòng)激發(fā)得以探測(cè)的反應(yīng)共振態(tài)，極大地提高了對(duì)反應(yīng)共振態(tài)的認(rèn)識(shí)。通過實(shí)驗(yàn)與理論對(duì)F+CHD3反應(yīng)中CH振動(dòng)激發(fā)對(duì)反應(yīng)的影響進(jìn)行研究，在實(shí)驗(yàn)上發(fā)現(xiàn)了CH振動(dòng)激發(fā)會(huì)導(dǎo)致處于某些振轉(zhuǎn)態(tài)反應(yīng)產(chǎn)物的輕度減少，與劉國(guó)平等人在Science上所報(bào)導(dǎo)的大大抑制該反應(yīng)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(dòng)激發(fā)能促進(jìn)該反應(yīng)的進(jìn)行，而實(shí)驗(yàn)所發(fā)現(xiàn)的抑制作用是由于所測(cè)量產(chǎn)物的局限性所引起的。另外，還在SO2光化學(xué)動(dòng)力學(xué)中發(fā)現(xiàn)了振動(dòng)激發(fā)對(duì)其反常同位素效應(yīng)的影響，研究了HOD振動(dòng)激發(fā)對(duì)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(yīng)成為可能，通過對(duì)J=0情況下H+CH4反應(yīng)的計(jì)算發(fā)現(xiàn)該模型有很高的精度。利用該模型，我們計(jì)算得到了H+CD4反應(yīng)的微分截面，與實(shí)驗(yàn)取得了高度吻合，表明已能較為精確地計(jì)算多原子反應(yīng)的態(tài)-態(tài)微分截面。

關(guān)鍵詞：多原子分子體系 化學(xué)反應(yīng)動(dòng)力學(xué) 振動(dòng)激發(fā)態(tài) 非絕熱量子動(dòng)力學(xué)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