Electron momentum spectroscopy with fixed-in-space molecules

固定空间分子的电子动量谱

基本信息

批准号：
13440170
负责人：
TAKAHASHI Masahiko
金额：
$ 7.81万
依托单位：
Okazaki National Research Institutes (2003)Tohoku University (2001-2002)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Through the last three decades of studies of binary (e,2e) spectroscopy or electron momentum spectroscopy (EMS), it has been demonstrated that the ionization reaction near the Bethe ridge is a sensitive probe for electronic structure and electron correlation. In particular, the ability to look at individual molecular orbitals in momentum space is the remarkable feature of this technique. However, EMS has not yet reached the stage of full use of its ability for intensive investigation on electronic structure of molecules. The reason for this may have been twofold; (1) a more complete knowledge of the binary (e,2e) reaction mechanism is an ever-increasing necessity as sophistication of experiments increases, and (2) the present EMS experiments measure averages over all orientations of gaseous molecules, resulting in enormous loss of information on electronic structure, anisotropy of the target wavefunction in particular. However, small cross section involved in the binary (e,2e) reaction has hindered one from developing EMS satisfactorily.Under these circumstances, we have constructed an electron-electron-fragment ion triple coincidence spectrometer. The spectrometer features remarkably high sensitivity for the two outgoing electrons by simultaneous detection in energy and momentum, and further it enables us to carry out (e,2e) experiments with fixed-in-space molecules based on their axial recoil fragmentation. By taking advantage of multichannel detection in. the spectrometer, we have successfully applied it to studies on collision dynamics of ionization excitation processes of the hydrogen molecule and directional momentum densities of the oxygen molecule. These are the first observation of molecular frame (e,2e) cross sections.

通过过去三十年对二元（e，2e）光谱或电子动量光谱（EMS）的研究，已经证明贝特脊附近的电离反应是电子结构和电子关联的敏感探针。特别是，能够观察动量空间中的单个分子轨道是该技术的显着特征。然而，EMS尚未达到充分发挥其对分子电子结构深入研究能力的阶段。造成这种情况的原因可能有两个： (1) 随着实验复杂程度的增加，对二元 (e,2e) 反应机制的更完整的了解变得越来越必要，(2) 目前的 EMS 实验测量气体分子所有方向的平均值，导致巨大的损失有关电子结构的信息，特别是目标波函数的各向异性。然而，二元(e,2e)反应涉及的小截面阻碍了EMS的令人满意的发展。在这种情况下，我们构建了一种电子-电子碎片离子三重符合谱仪。该光谱仪通过同时检测能量和动量，对两个出射电子具有非常高的灵敏度，并且它使我们能够基于固定空间分子的轴向反冲碎片进行（e，2e）实验。利用光谱仪的多通道检测技术，我们成功地将其应用于氢分子电离激发过程和氧分子定向动量密度的碰撞动力学研究。这是分子框架 (e,2e) 横截面的首次观察。