Abstract

We report a combined experimental and theoretical study on the electron-impact ionization dynamics of H₂ at an impact-energy of 520 eV. The molecular-frame fivefold-differential cross sections were measured for electron emission in the plane perpendicular to the incoming projectile beam. An (e, 2e + ion) triple coincidence method was used covering projectile scattering angles of 6.5°, 10.0° and 20.0° and ejected energies of 20 eV and 30 eV. The experimental cross sections are compared with results from the multi-center distorted-wave (MCDW) as well as the molecular three-body distorted wave (M3DW) approaches. M3DW is in overall better agreement with the measured data in the binary lobes than MCDW, while the intensity of recoil lobes are underestimated by both theories. Furthermore, we examine the presence of two-center interference patterns by comparing the experimental cross section ratios between mutually perpendicular alignment angles of the molecular axis with that predicated by the interference model. Agreement with the interference model is found only for Bethe ridge kinematics, i.e. in the binary peak region and with the ejected electron momentum being roughly equal to the momentum transfer. Finally, we suggest a modified interference formula for the recoil peak which takes into account the backscattering of the ejected electron in the ionic potential.

Graphical abstract

中文翻译：

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高冲击能下H 2的分子框架（e，2e）电离动力学

摘要

我们报告了H ₂的电子碰撞电离动力学的组合实验和理论研究在520 eV的冲击能量下。在垂直于入射射束的平面内，测量了分子框架的五倍微分截面的电子发射。使用（e，2e +离子）三重符合方法，覆盖了6.5°，10.0°和20.0°的弹丸散射角以及20 eV和30 eV的射出能量。将实验横截面与多中心畸变波（MCDW）以及分子三体畸变波（M3DW）方法的结果进行比较。与MCDW相比，M3DW与二值瓣中的测量数据总体上具有更好的一致性，而两种理论都低估了后坐瓣的强度。此外，我们通过比较分子轴的相互垂直排列角与实验模型所确定的分子横截面之间的实验截面比，来研究两中心干涉图的存在。仅在Bethe脊运动学上，即在二元峰区域内，并且与射出的电子动量大致等于动量传递，才能找到与干扰模型的一致性。最后，我们提出了一个针对反冲峰的修正干涉公式，该公式考虑了喷射电子在离子电势中的反向散射。

图形概要