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Theoretical Study for Dynamics of Molecules near Metal Surfaces

金属表面附近分子动力学的理论研究

基本信息

批准号：
04640367
负责人：
OKIJI Ayao
金额：
$ 1.22万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04640367/
关键词：
potential energy surface steric effect non-adiabatic effect desorption induced by electronic transition pump-probe spectroscopy vibrational relaxation nonharmonicity of intramolecular vibration dissociative adsorption of rotating molecules /

项目摘要

In order to clarify the reactivity of molecules at metal surfaces, it is necessary to build up accurate knowledge of potential energy surfaces (PES) corresponding to the ground state energy and excited state energy of electron system, and relaxation mechanism of excited states. From this view, theoretical study has been done on the reactivity of molecules at metal surfaces. The obtained results are summarized as follows.1.On the basis of comparison between experimental and calculational results for scattering dynamics of diatomic molecules from metal surfaces, the dependence of PES on orientation of molecular axis has been clarfied for NO/Ag (111). 2. In the excitation process of intramolecular vibration in the scattering of molecules from metal surfaces, energy transfer from electron system to intramolecular vibrational degree of freedom, i.e., non-adiabatic effect plays an improtant role. 3. On the analysis of transient absorption difference spectra for intra-molecular vibration of C … More O on Pt (111) observed recently by the use of ultrashort-pulse laser, deviation of vibrational states from harmonicity and relaxation time of excited vibrational states at metal surfaces are clarified. 4. A new model is proposed for photo-stimulated desorption, in which the coupling between degrees of freedom of electron system and translational motion of adsorbates is taken into account from a microscopic viewpoint. On the basis of the comparison between model calculations and the experimental results for desorption probability, the validity of the proposed new model is clarified. 5. Dissociative adsorption in H2/Cu system is a paradigm of activated processes. There are two kinds of effects of rotational excitation on the dissociative adsorption, i.e., steering effect and energy transfer effect. The former is dominant for low rotational energy region and the latter for high energy region. As a result, non-monotonous dependendce of sticking probability on rotational excitation can be observed. Less

为了阐明分子在金属表面的反应性，有必要建立准确的电子系统基态能和激发态能对应的势能面（PES）和激发态的弛豫机制的知识。从这一观点出发，对分子在金属表面的反应性进行了理论研究。所得结果总结如下：1。通过对金属表面双原子分子散射动力学的实验结果与计算结果的比较，阐明了NO/Ag（111）的PES与分子轴取向的关系。2. 在分子从金属表面散射的分子内振动激发过程中，从电子系统向分子内振动自由度的能量传递，即非绝热效应起着重要作用。3. 通过对最近用超短脉冲激光观测到的C…More O在Pt（111）上的分子内振动的瞬态吸收差谱分析，阐明了金属表面振动态与谐波的偏差和激发振动态的弛豫时间。4. 提出了一种新的光激解吸模型，该模型从微观角度考虑了电子系统自由度与吸附物平动运动之间的耦合关系。通过模型计算与实验结果的比较，阐明了新模型的有效性。5. H2/Cu系统的解离吸附是一种典型的活化过程。旋转激励对解离吸附有两种影响，即转向效应和能量传递效应。前者在低旋转能区占主导地位，后者在高能区占主导地位。因此，可以观察到粘着概率与旋转激励的非单调关系。少