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

表面吸附分子与其模型团簇电子结构对应关系的研究

基本信息

批准号：
13640498
负责人：
MISAIZU Fuminori
金额：
$ 2.56万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

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

在这个项目中，通过光电离质谱、负离子光电子能谱、簇离子的光解以及量子化学计算，研究了从碱原子到组成分子的簇内电子转移以及随后的化学反应。检查由碱原子 M（M=Li、Na 和 K）和丙烯腈（AN；CH2=CHCN）分子组成的系统的团簇依赖性稳定性这些簇被认为是本体溶液中阴离子聚合反应的初始系统的微观模型，在M(AN)_n^+的光电离质谱中，通常在n=3时观察到强离子信号。通过电子从金属原子转移到乙烯基分子，然后进行团簇内阴离子低聚，产生具有取代环己烷环结构的稳定物质，这些 n=3 的团簇也被发现非常稳定。根据光电离之前的光解离实验，基于密度泛函理论的 Na(AN) 量子化学计算也支持从金属原子到分子的团簇内电子转移。除了上述中性系统之外，阴离子的团簇内反应也存在。 NaAN团簇也通过质量选择光电子能谱进行了检查。在这个实验中，我们获得了团簇负离子的光电子能谱，这些负离子是通过激光汽化和TOF质量选择产生的。利用磁瓶TOF电子能量分析仪，发现Na(AN)_3-的光电子能谱与(AN)_3-以及1,3的光电子能谱相似。 Kondow 及其同事获得的 5-环己烷三甲腈分子负离子这一观察结果表明 Na(AN)_3- 中的多余电子促进了簇内阴离子齐聚和环状反应。低聚物的产生与中性 M-乙烯基分子系统的讨论相同。