Study of the Correspondence in Electronic Structure between the Molecules Adsorbed on Surface and Their Model clusters

在本项目中，利用光电离质谱、负光电子谱、簇离子光解离以及量子化学计算，研究了从碱原子到组成分子的簇内电子转移和随后的化学反应。在光离研究中，研究了由碱原子M （M=Li， Na和K）和丙烯腈（an; CH2=CHCN）分子组成的体系中团簇的尺寸依赖性稳定性。这些团簇被认为是本体溶液中阴离子聚合反应初始体系的微观模型。在M(AN)_n^+的光离质谱中，在n=3处通常观察到强离子信号。这个神奇的数字可以解释为电子从金属原子转移到乙烯基分子，然后在簇内阴离子低聚化，产生具有取代环己烷环结构的稳定物质。这些n=3的团簇在光电离之前的光解离实验中也被发现是非常稳定的。基于密度泛函理论的Na（AN）量子化学计算也支持簇内电子从金属原子向分子的转移。除了上述中性体系外，还通过大量选择光电子能谱研究了NaAN簇中负离子的簇内反应。在本实验中，我们利用磁瓶TOF电子能量分析仪获得了激光汽化产生的团簇负离子的光电子能谱，并在TOF质谱仪中选择质量。得到的Na(AN)_3-光电子能谱与（AN）_3-光电子能谱具有相似的能带结构，也与Kondow等人得到的1,3,5-环己三腈分子负离子光电子能谱具有相似的能带结构。这一观察结果表明，Na(AN)_3-中的多余电子促进了簇内阴离子低聚，并产生了中性m -乙烯基分子体系的环状低聚物。少

In this project, intracluster electron transfer from an alkali atom to constituent molecules and the following chemical reactions have been investigated by photoionization mass spectroscopy, negativeion photoelectron spectroscopy, photodissociation of cluster ions, and also by quantum chemical calculations. In the photoionization study, size-dependent stability of clusters is examined for the systems consisting of an alkali atom M (M=Li, Na, and K) and acrylonitrile (AN; CH2=CHCN) molecules These clusters are considered as microscopic models of initial systems for anionic polymerization reaction in the bulk solution. In the photoionization mass spectra of M(AN)_n^+, strong ion signals were observed commonly at n=3. This magic number can be explained by the electron transfer from the metal atom to vinyl molecules followed by intracluster anionic oligomerization to produce stable species with substituted cyclohexane ring structures. These clusters with n=3 were also found to be extraordi … More nary stable from the photodissociation experiments prior to photoionization. Quantum chemical calculation for Na(AN) based on density functional theory also supports the intracluster electron transfer from the metal atom to molecules.Along with the neutral systems noted above, intracluster reactions in the negative ions of the NaAN clusters have also been examined by mass-selected photoelectron spectroscopy. In this experiment, we obtained photoelectron spectra of cluster negative ions, which were produced by laser vaporization and mass selected in a TOF mass spectrometer, by using a magnetic-bottle TOF electron energy analyzer. The obtained photoelectron spectrum of Na(AN)_3- were found to have the similar band structure with that of (AN)_3- and also with that of the 1,3,5-cyclohexanetricarbonitrile molecular negative ion obtained by Kondow and his coworkers. This observation indicates that the excess electron in Na(AN)_3- promotes the intracluster anionic oligomerization and that the cyclic oligomer is produced as discussed for the neutral M-vinyl molecules systems. Less