Studies on relaxation processes of core-excited molecules followed by deformation

分子软X射线光谱研究领域的一个重要和热点问题，即核电子激发和核电子电离后的衰变动力学，涉及到核激发分子的弛豫动力学。多符合技术是研究核孔形成后态-态解离动力学的有力工具。然而，许多以前开发的实验装置，为这样的研究并不那么令人满意，因为它们中的每一个都有一定的限制，其应用。这里开发的新设备是在法国奥赛的LURE开发的世界著名的EPICEA II的能力的自然扩大，通过引入两个二维探测器，具有足够快的响应，电子和离子检测。为了满足测量电子或离子初动量的空间聚焦条件，设计了一种新型的双环形静电分析器。在UVSOR设备的新建造的束线BL 4 B处进行的分析器的性能测试的结果清楚地表明，即使对于简单的电子能谱，也强烈期望进一步的改进。最近在LURE获得的结果，使用与我们有类似的概念开发的新设备，直接显示的重要作用的核心激发态的分子几何形状变形的H2O和CO2，这导致特定的碎裂通道。这些工作正是我们在现有的实验装置发展之后所要做的，并为我们未来的系统改进提供了动力。一个新的飞行时间质谱仪与二维检测器将在不久的将来开发和引入到我们的实验装置。

This work intends to cover an important and hot topic in the research field of molecular soft X-ray spectroscopy, in which the decay dynamics following core-electron excitation as well as core-electron ionization for molecules has been extensively studied over the past two decades, which is related to the relaxation dynamics of core-excited molecules. As is widely recognized, the multi-coincidence technique is a powerful tool to investigate state-to-state dissociation dynamics following the core-hole creation. However, many experimental apparatuses previously developed for such investigations were not so close to satisfaction, because each of them has a certain limitation for its application. The new apparatus developed here is a natural enlargement of the capability of the world-famous EPICEA II developed at LURE, Orsay, France, by introducing two two-dimensional detectors with sufficiently fast response, both to electron and ion detections. A great deal of effort has been put into designing a new electrostatic analyzer with a double toroidal shape, in order to satisfy spatial focusing condition for determining the initial momenta of electrons or ions. The result of the performance tests for the analyzer performed at a newly constructed beamline BL4B of the UVSOR facility clearly indicate that further improvements are strongly desired even for the simple electron spectroscopy. The recent results obtained at LURE using a new apparatus developed with the similar concepts as we have, show directly the significant role of the molecular geometry deformation of the core-excited states in H2O and CO2, which induces to specific fragmentation channels. This kind of work is exactly what we would like to perform after the development of the present experimental setup, and gives us an impetus for future improvement of our system. A new time-of-flight mass spectrometer with a two-dimensional detector will be developed and introduced to our experimental setup in the near future.