Dynamics of Site-Specific Ion Desorption Reactions

位点特异性离子解吸反应的动力学

基本信息

批准号：
16205002
负责人：
TANAKA Kenichiro
金额：
$ 29.54万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16205002/
关键词：
Soft X-ray Synchrotron Radiation Auger Decay Core Electron Excitation Photon Stimulated Ion Desorption Site-Specific Reaction Self-Assembled Monolayer Density Functional Theory

项目摘要

We investigated site-selective chemical bond scission by core excitation for methyl-ester terminated self-assembled monolayer (SAM) in order to improve the selectivity and to elucidate the dynamics of this reaction, and obtained many important results as follows:(1) Primary bond scission occurs within ester group and its selectivity becomes much higher than PMMA. We have succeeded to evaluate direct and indirect processes quantitatively and obtained the selectivity is more than 90% for SAM and 60% for PMMA.(2) From polarization dependent experiments, it was found that ions which desorb selectively indicate significant polarization dependence, while non-selective ions rarely show the dependence. These findings indicate that initial memory of primary excitation is effectively conserved during reactions. From these results we proposed an active control of chemical bond scission just by changing an angle of incident radiation.(3) Selective bond scission of O-CH_3 could be achieved at both … More resonant excitations of o^*(O-CH_3)← C_<1s>(O-CH_3) and O_<1s>(O-CH_3). Distribution of CH_n^+ (n=1-3), however, is different at the position of primary excited atoms. At C excitation, Auger final energy is concentrated within removing CH_3+ and is effectively used for further fragmentation (named as "Hard-Cut"), but at O excitation, Auger energy easily diffuses into the substrate and not effectively used for the fragmentation (named as "Soft-Cut").(4) The dynamics of resonant core-excited states have been investigated theoretically by DFT theory and succeeded to find systematic relationship between chemical bond and potential gradient in the core-excited state, which plays an important role for the selective bond scission. Some general regularities were found: The gradient of core-excited state becomes more negative with increasing sum of the atomic numbers of bonding pair atoms, atomic number by core-excited atom, and the bond order. These rules are important to predict and design the site-selective bond scission reactions. Less

我们通过核心兴奋来研究甲基终止的自组装单层（SAM）的核心化学键科学，以提高选择性并阐明该反应的动力学，并获得了许多重要结果，如下所示：（1）原发性键科学在酯组中发生，其选择性比PMMA高得多。我们已经成功地评估了直接和间接过程的定量和间接过程，并且获得的SAM的选择性超过90％，而PMMA的选择性超过60％。（2）从偏振依赖性实验中，发现对呼吸性的离子选择性地表明显着极化依赖性，而非选择性离子很少显示依赖性。这些发现表明，在反应过程中，初始兴奋的初始记忆有效地保存了。从这些结果中，我们提出了仅通过改变入射辐射角的积极控制化学键科学。（3）在这两个方面都可以实现O-CH_3的选择性键键孔。但是，在主要激发原子的位置，Ch_n^+（n = 1-3）的分布有所不同。在C兴奋时，钻钻的最终能量集中在去除CH_3+的内部，可有效地用于进一步的分裂（称为“硬切割”），但令人兴奋的，令人兴奋的，螺旋钻的能量很容易扩散到底物中，而不是有效地用于碎片，并且在构造的“软切子”中，通过研究了核心核心的状态。核心兴奋状态的潜在梯度，这对于选择性粘结分裂起着重要作用。发现了一些一般规律性：随着键盘原子原子的原子数增加，核心数量的原子数，核心激发原子的原子数和键顺序，核心兴奋状态的梯度变得更加负面。这些规则对于预测和设计现场选择性的键合反应很重要。较少的