A Precision Measurement of the Dynamics Involved in the Decaying of Molecular Shape Resonance States

在低能电子与分子碰撞中观察到的共振条件可以大致分为两种形式：形状共振--电子暂时被分子势俘获，以及费什贝克共振--通过电子激发进行。无论是在分子与软X射线光子碰撞中观察到的芯级吸收光谱，还是在电离阈值以上区域观察到的吸收光谱，都是由形状共振主导的。在光子-分子碰撞中观察到的这种形状共振是由于光电子被分子势暂时俘获并随后释放的过程，即理想情况下与低能分子碰撞中的形状共振现象相同。为了研究形状共振现象所涉及的动力学，我们小组开展了一项研究，包括系统地研究低能电子碰撞中的形状共振和在高分辨率核心能级光电离中观察到的形状共振。在比较芯级电离态和基态时，虽然库仑势不同，但价电子组态是相同的。围绕这一点，我们研究了具有相似对称性、能量、振动和电子激发的分子在电子碰撞和芯能级光电离两种情况下的形状共振现象。这不仅解释了多体系统中的形状共振现象，而且表明绝热势近似在描述电子和原子核的运动时是失败的。为了实现这一目标，使用索菲亚大学的低能电子碰撞装置研究了一些基本分子，而在Spring-8上使用芯级光电子和光电子-离子之间的符合技术进行了实验。我们了解了分子形状共振态衰变所涉及的动力学。

The resonance condition observed in the collision between a low-energy electron with a molecule can be broadly classified into two forms; shape resonance-whereby the electron is temporarily trapped by the molecular potential, and the Feshback resonance-which proceeds via electronic excitation. Both the core-level absorption spectrum observed in molecular collisions with soft X-ray photons and that observed in the region above the ionization threshold are dominated by shape resonances. This shape resonance observed in the photon-molecule collision is due to a process whereby the photoelectron is temporarily trapped by the molecular potential and later released, that is, ideally the same as the shape resonance phenomenon in low-energy molecular collisions. With the aim of investigating the dynamics involved in shape resonance phenomena, our group has embarked on a research involving systematic studies of shape resonances in low-energy electron collisions and those observed in high resolution core-level photoionization. In comparing the core-level ionization state with the ground state though the Coulomb potentials differ, the valence electronic configurations are identical. While focusing on this point, we studied the shape resonance phenomena for molecules with similar symmetry, energy, vibrational and electronic excitation for both electron collision and core-level photoionization. This not only managed to elucidate on the shape resonance phenomena in a many-body system, but also showed the failure of the adiabatic potential approximation in describing the motion of the electron and nucleus. In order to achieve this goal, some basic molecules were studied; using the low-energy electron collision apparatus at Sophia University, while experiments were carried out at the Spring-8 using the coincidence technique between the core-level photoelectron and the photoelectron-ion. We understood the dynamics involved in the decaying of the molecular shape resonance states.