Study of multiple photoionization processes by multi-electron coincidence spectroscopy

我们用多电子符合谱研究了原子和分子的多重光电离过程。为此，研制一种具有高探测效率、同步辐射脉冲时间结构的磁瓶飞行时间电子能谱仪是非常重要的。对于Ne原子，我们得到了入射光子能区从阈值到200 eV的最终态选择双光电离截面，其中两个电子是从2s和2p外壳电离的。这是第一个精确的实验数据，为现有理论提供了一个严格检验的机会。在Xe原子中，4p光电子峰的反常行为自1976年瑞典研究小组首次发现以来一直受到关注，4p；lt；1/2和gt；峰被完全抹掉，4p；lt；3/2&gt；峰呈复杂结构。我们发现了4d^2双电离的反常增强，并对e…进行了精确的分析这两个电子之间的能量关联更强，这表明Xe^&lt；2&gt；4d^&lt；-2&gt；态是通过Xe 4p-1态的Super-Coster-Kronig过程产生的，这是30年前理论上预测的，现在用一种新的强大的符合谱实验证明了这一点。此外，我们还研究了CO分子的双光电离，其中一个外层电子与一个C1s或O1ss电子的内层电离同时发射。通过对这两个电子的符合测量，我们发现在光谱特征上，CO^&lt；2&gt；态的性质表现为定域价空穴与核心空穴之间的相互作用。这些结果已在学术期刊上发表，并在接下来的国内外会议上公布。虽然到目前为止，我们对两个电子起重要作用的双光电离过程感兴趣，但我们将使用在这笔拨款的帮助下完成的机械斩光器来发展我们的研究，三个电子过程。事实上，我们已经在Ar三重电离方面取得了有趣的结果，这些结果很快就会提交给一本杂志。较少

We have carried out multi-electron coincidence spectroscopy for investigating multiple photoionization processes of atoms and molecules. For this aim, it is very important to have a magnetic bottle time-of-flight electron spectrometer with high detection efficiency, and pulsed time structure of synchrotron radiation. For Ne atoms, we have obtained the final state-selective double photoionization cross sections for the incident photon energy region from the thresholds to 200eV, where the two electrons are ionized from the 2s and 2p outer shells. This is the first precise experimental data supplying an opportunity of rigorous examination for existing theories. In Xe atoms, the abnormal behavior of 4p photoelectron peaks has been paid attention since its first observation by Swedish group in 1976 ; the 4p_<1/2>peak is completely smeared out and the 4p_<3/2>peak is appeared as a complex structure. We have found an abnormal enhancement of 4d^2 double ionization, and analyzed precisely the e … More nergy correlation between these two electrons, which reveals that the Xe^<2+> 4d^<-2> states are produced via Super-Coster-Kronig processes of Xe+ 4p-1 states, which was predicted theoretically 30 years ago, and now proved experimentally with a new powerful coincidence spectOscopy. Furthermore, we have studied double photoionization of CO molecules, where an outer shell electron is simultaneously emitted with inner shell ionization of a C1s or O1ss electron. With coincidence measurements of these two electrons, we have found on the spectral features that the properties of the CO^<2+> states are characterized by the interaction between the localized valence holes and the core holes.These results have been reported in the academic journals and presented at the internal and international conferences as shown in the next pages. While so far we have been interested in double photoionization processes where two electrons makes important roles, we will develop our study three electrons processes, using a mechanical light chopper accomplished with an aid of this grant. Actually, we have already obtained interesting results on Ar triple ionization, which will be submitted to a journal very soon. Less