Using electron spectroscopy technique we have measured the absolute double differential cross sections (DDCS) of electrons emitted in collisions of 200 keV protons on He, CH${}_4$ and O${}_2$ and 5.5 MeV/u bare C ions colliding on O${}_2$. The emitted electrons were measured in the energy range from 1 eV to 400 eV for He and CH${}_4$ targets and upto 600 eV for O${}_2$ to include the K-LL Auger line of oxygen. The electrons were detected over different emission angles varying from 20${}^0$ in the extreme forward direction to 160${}^0$ in the backward direction. The single differential cross section (SDCS) and total cross section (TCS) have been deduced from the measured DDCSs spectra for all the targets. The DDCS and SDCS have been compared with the state-of-the-art continuum distorted wave-eikonal initial state (CDW-EIS) theoretical model. The CDW-EIS provided an excellent agreement with the oxygen data at MeV energy, whereas the deviation in case of keV-energy was substantial, inspite of having nearly the same perturbation strength. The forward-backward angular asymmetry showed a saturation effect in case of keV energy protons but no such signature was observed for the high energy collision. A systematic analysis reveals that the asymmetry at low electron energy is sensitive to the atomic or molecular structure associated and is in close agreement with the theory.

中文翻译：

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使用200keV质子和5.5MeV / u裸C离子对原子和分子进行电离：取决于能量的碰撞动力学

使用电子光谱技术，我们测量了在He，CH上200 keV质子的碰撞中发射的电子的绝对双微分截面（DDCS）${}_4$ 和O${}_2$ 和5.5 MeV / u裸C离子碰撞在O上${}_2$。对于He和CH，在1 eV至400 eV的能量范围内测量了发射的电子${}_4$ 目标和高达600 eV的O${}_2$包括氧气的K-LL俄歇线。在20至20的不同发射角上检测到电子${}^0$ 在极端的前进方向到160${}^0$在向后的方向。从所有目标的测量DDCSs光谱中推导出了单微分截面（SDCS）和总截面（TCS）。DDCS和SDCS已与最新的连续谱畸变波-本征初始状态（CDW-EIS）理论模型进行了比较。CDW-EIS与MeV能量下的氧气数据非常吻合，而keV能量下的偏差却很大，尽管其扰动强度几乎相同。在keV能量质子的情况下，前后角度不对称显示出饱和效应，但对于高能碰撞没有观察到这样的信号。系统分析表明，低电子能量下的不对称性对相关的原子或分子结构敏感，并且与该理论非常吻合。