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

本项目利用光电离质谱、负离子光电子能谱、团簇离子的光解离以及量子化学计算研究了团簇内电子从碱金属原子到组成分子的转移以及随后的化学反应。在光电离研究中，考察了由碱金属原子M（M=Li，Na，K）和丙烯腈（AN; CH_2 =CHCN）组成的体系团簇的尺寸依赖稳定性。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^+的光电离质谱中，通常在n=3处观察到较强的离子信号。这个幻数可以解释为电子从金属原子转移到乙烯基分子，然后通过簇内阴离子低聚产生具有取代的环己烷环结构的稳定物种。这些n=3的簇也被发现是extraordi ...更多信息 在光电离之前的光解离实验中不稳定。基于密度泛函理论的Na（AN）的量子化学计算也支持了团簇内电子从金属原子到分子的转移.沿着上述中性体系，NaAN团簇负离子的团簇内反应也被质量选择光电子能谱研究.本实验采用磁瓶式飞行时间电子能量分析仪，对激光蒸发产生的团簇负离子进行了质量选择，获得了团簇负离子的光电子能谱。Na（AN）_3 ~-的光电子能谱与（AN）_3 ~-和Kondow等人的1，3，5-环己烷三腈分子负离子的能带结构相似。结果表明，Na（AN）_3-中的过剩电子促进了簇内阴离子齐聚反应，并产生了与中性M-乙烯基分子体系相同的环状齐聚物。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