多原子体系的化学反应动力学研究

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

利用自主研发的窄线宽OPO激光和受激Raman技术首次在交叉分子束中实现了对氢气振动激发态的研究,并在F+HD(v=1)→HF+D反应中观察到只能通过反应物振动激发得以探测的反应共振态，极大地提高了对反应共振态的认识。通过实验与理论对F+CHD3反应中CH振动激发对反应的影响进行研究，在实验上发现了CH振动激发会导致处于某些振转态反应产物的轻度减少，与刘国平等人在Science上所报导的大大抑制该反应有着明显的差异。更有意思的是我们理论研究发现总的来说CH振动激发能促进该反应的进行，而实验所发现的抑制作用是由于所测量产物的局限性所引起的。另外，还在SO2光化学动力学中发现了振动激发对其反常同位素效应的影响，研究了HOD振动激发对其在Cu(111)面解离吸附的影响。在理论方法发展方面，发展了一种新的减维模型，使在态-态水平研究X+YCZ3→XY+CZ3类型的反应成为可能,通过对J=0情况下H＋CH4反应的计算发现该模型有很高的精度。利用该模型，我们计算得到了H+CD4反应的微分截面，与实验取得了高度吻合，表明已能较为精确地计算多原子反应的态-态微分截面。

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