Summary of Research Project Results under JSPS FY2002
"Research for the Future Program"

1.Research Institution Hiroshima University
2.Research Area Physical and Engineering Science
3.Research Field Photoscience
4.Term of Project FY 1998 - FY 2002
5.Project Number 98P01202
6.Title of Project Molecular Knife - Control of Chemical Reactions by Core Excitation

7.Project Leader
Name Institution,Department Title of Position
Kenichiro, Tanaka Hiroshima University, Graduate School of Science Professor

8.Core Members

Name Institution,Department Title of Position
Atsunari, Hiraya Hiroshima University, Graduate School of Science Professor
Ko, Saito Hiroshima University, Graduate School of Science Professor

9.Summary of Research Results

  In this project, we have aimed at realization of ultimate control of chemical reactions "molecular knife" using core excitation, while several unique reactions by core excitation have been discovered and mechanism of such reactions have been clarified in intimate cooperation with "surface chemical reaction", "gas phase chemical reaction" and "chemical reaction theory" groups.
  In "surface chemical reaction", site-specific reactions were discovered for various surface molecules and correlations between desorbed ions and core-excited and Auger final states were examined in detail. Whole pictures of reaction mechanism and aspects for realizing site-selective bond scission were elucidated, and a scenario for realizing "molecular knife" was proposed. While this scenario was verified, with the aim of improvement in controllability of site-selective bond scission, systematic research for several self-assembled monolayers using the linearly polarized radiation were carried out. By choosing energy and incident angle of radiation, it succeeded in improving controllability and efficiency of the site-selective bond scission.
  In "gas phase chemical reaction", new types of excited-state and Auger final-state selective reactions were discovered. Mechanism of such unique reactions was successfully elucidated by using newly developed coincidence measurements. In addition to the main subject of this project, applicability of angular distribution in ionic fragments was demonstrated as a powerful tool for assignment of electronic states for large molecules.
  In "chemical reaction theory", following studies have been carried out in order to explore the origin of site-selectivity in core-excited reactions. First, theoretical calculations for core excitation process were performed by the density functional theory, and core-excited states for various molecules were quantitatively identified. Second, new theoretical procedure for Auger decay process originated by electron population analysis was developed, and experimental results were well explained. Third, a bond dissociation factor was firstly introduced, and site-selectivity after Auger decay was quantitatively explained by this factor.

10.Key Words
(1)Core Excitation   (2)Synchrotron Radiation   (3)Synchrotron Radiation Chemistry
(4)Soft X-Ray Chemistry   (5)Site-Specific Dissociation   (6)Control of Chemical Reaction
(7)Molecular Knife   (8)Auger Process   (9)Molecular Orbital Calculation