Three-dimensional imaging of molecular orbitals by the electron-electron-ion coincidence experiment

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Electron momentum spectroscopy (EMS) allows us to measure molecular orbital pattern. It. consists of a high-energy electron-impact ionization experiment in which kinematics of all the electrons are fully determined with coincident detection of the two outgoing electrons. While a variety of molecular orbitals have been widely studied by EMS, the resulting information is limited only to the radial part of wavefunction due to randomly oriented target molecules. This project has aimed to develop a new method, based on EMS, for looking at three-dimensional orbital patterns by further coincident detection of fragment-ion.Within the period of the present grant-in-aid the following attempts have been made.1. An electronic circuit and a fragment-ton detector have been constructed. By combining these with the present EMS spectrometer an apparatus for this project has been completed.2. Coincidence experiments for inelastically scattered electrons and fragment-tons, which are generated by the elec … More tron-impact inner-shell excitation, have been carried out for nitrogen molecule. While coincidence signal has been successfully detected, the statistics is not good. This observation indicates that the imaging technique is best suited for fragment-ion detection in this project.3. Angular correlations between photoelectrons and fragment-ions have been studied for several diatomic molecules. From comparison of experiments and theory it has been found that most of valence-shell ionization transitions are followed by the fast ion dissociation processes, and can be used for this project.4. A new EMS apparatus has been constructed, where for the two outgoing electrons two position-sensitive detectors are employed. Their ability of simultaneous energy- and angle-dispersive measurements gives rise to considerable improvement in data gathering speed.Application of the imaging technique to fragment-ion detection as well as the electrons are under consideration in order to raise the methodology here to become brand-new spectroscopy for orbital pattern imaging. Less