Absolute cross sections for electron impact ionization and dissociation of the planetary atmospherically important molecule, methane, have been measured in a wide energy range from 350 to 8000 eV using an ion momentum imaging spectrometer. The partial ionization cross sections (PICSs) of ionic fragments CH4+, CH3+, CH2+, CH+, C+, H+ and H2+, as well as five dissociation channels are obtained. The total ionization cross sections are also deduced by summing up the PICSs for all the observed ions. The PICSs of the ionic fragments at electron impact energies above 2000 eV and the PICSs of the dissociation processes are reported for the first time. The comparison and evaluation of the previous measurements reveals that the data of Lindsay and Mangan (2003) are in global agreement with present results, recommending reliable cross sections for electron impact ionization of methane from threshold to 8000 eV.

中文翻译：

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甲烷电子碰撞电离和解离的绝对截面为 350 至 8000 eV


使用离子动量成像光谱仪在 350 至 8000 eV 的宽能量范围内测量了行星大气重要分子甲烷的电子碰撞电离和解离的绝对截面。获得了离子片段 CH4+、CH3+、CH2+、CH+、CH+、C+、H+ 和 H2+ 的部分电离截面 （PICS） 以及 5 个解离通道。总电离截面也可通过将所有观察到的离子的 PICS 相加来推导出。首次报道了电子碰撞能量高于 2000 eV 时离子片段的 PICS 和解离过程的 PICS。对先前测量的比较和评估表明，Lindsay 和 Mangan （2003） 的数据与目前的结果一致，推荐了甲烷电子碰撞电离从阈值到 8000 eV 的可靠横截面。