Formation and decay of superexcited molecules as studied by synchrotron-radiation photon and electron collisions

1.同步辐射光子碰撞研究双激发分子我们测量了甲烷、氨、水和乙烯在10-40 eV入射光子能量范围内光激发甲烷、氨、水和乙烯时，在紫外区和可见光范围内荧光发射截面的绝对值。有趣的是，在内价范围内双激发甲烷、氨和水的Balmer荧光的振子强度相当于这些分子的附近单空穴单电子超激发态的振子强度，这是独立电子模型崩溃的强烈迹象。用符合电子能量损失谱研究了超激发态分子。符合电子能量损失谱是研究S…的一种很好的手段更多的超激发分子，这是我们小组几年前开发的。测量的电子能量损失谱与电子与分子碰撞过程中中性碎片的真空-紫外荧光发射相吻合，揭示了电子与分子碰撞中的超激发态结构。我们测量了氮分子、氧分子和甲烷分子在不同入射电子能量和散射角下价范围内的重合电子能量损失谱。有趣的是，氮的光学禁止双激发态比允许的双激发态具有更大的贡献。测量了氧的时间分辨符合电子能量损失谱，对超激发氧分子进行了详细的研究。在高于25 eV的范围内，发现了由甲烷双激发态引起的强峰。配备位置灵敏电子探测器的第二代系统已经被开发出来，以更高效、更少的方式获得光谱

1.Doubly excited molecules as studied by synchrotron-radiation photon collisionsWe have measured the absolute values of the cross sections for the emission of fluorescences in the ultraviolet and visible ranges from neutral fragments in the photoexcitation of methane, ammonia, water and ethylene as a function of incident photon energy in the range 10-40 eV. Interestingly, the oscillator strengths for Balmer fluorescences from doubly excited methane, ammonia and water in the inner valence range amount to the magnitudes comparable to those from nearby single-hole one-electron superexcited states of these molecules, which is a strong indication of the breakdown of the independent electron model. An important role of the doubly excited ethylene has been found in the cross section curves for Balmer fluorescences.2.Superexcited molecules as studied by the coincident electron-energy-loss spectroscopyThe coincident electron-energy-loss spectroscopy is an excellent means for investigating the s … More uperexcited molecules, which was developed by our group a few years ago. The electron energy-loss spectra are measured in coincidence with the emission of the vacuum-ultraviolet fluorescences from neutral fragments in electron collisions with molecules, in which the structures attributed to the superexcited states are shown up. We have measured the coincident electron-energy-loss spectra of molecular nitrogen, molecular oxygen, and methane in the valence range at several incident electron energies and scattering angles. Interestingly the optically-forbidden doubly excited states of nitrogen give larger contribution than the allowed doubly excited states. The time-resolved coincident electron-energy-loss spectra of oxygen have been measured to study the superexcited oxygen molecules in detail. The intense peaks attributed to the doubly excited methane have been found in the range above 25 eV. The second-generation system equipped with a position-sensitive detector for electrons has been developed to obtain the spectra much more efficiently Less