Study of multiple photoionization processes by multi-electron coincidence spectroscopy

我们利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，具有高探测效率的磁瓶飞行时间谱仪和同步辐射脉冲时间结构是非常重要的。对于Ne原子，我们得到了入射光子能量范围从阈值到200 eV的末态选择性双光电离截面，其中两个电子分别从2s和2 p外层电离。这是第一个精确的实验数据，为现有理论提供了严格检验的机会。自1976年瑞典小组首次观测到4p光电子峰以来，4p光电子峰的异常行为一直受到人们的关注，4p_<1/2>峰被完全消除，4p_<3/2>峰呈现复杂结构。我们发现了4d^2双电离的异常增强，并对4d^2双电离的增强进行了精确的分析。 关于我们 这两个电子之间的能量关联揭示了电子的π ^&lt;2+&gt; 4d^+<-2>态是通过π ^+ 4p-1态的Super-Coster-Kronig过程产生的，这一点在30年前就被理论预言，现在用新的强符合电子显微术得到了实验证实。此外，我们还研究了CO分子的双光电离，即外层电子与内壳层C1 s或O 1 ss电子同时发射，通过对这两个电子的符合测量，我们从光谱特征上发现，CO^&lt;2+&gt;态的特征是局域价空穴和芯空穴之间的相互作用。这些结果已在学术期刊上报道，并在国内和国际会议，如下页所示。虽然到目前为止，我们一直对双光电离过程感兴趣，其中两个电子起着重要作用，但我们将利用该补助金完成的机械光斩波器来发展我们的研究三电子过程。实际上，我们已经获得了关于Ar三重电离的有趣结果，这些结果将很快提交给期刊。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