An (e, 2e+ ion) study of electron-impact ionization and fragmentation of tetrafluoromethane at low energies
An (e, 2e+ ion) study of electron-impact ionization and fragmentation of tetrafluoromethane at low energies
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DOI：
10.1140/epjd/e2017-80665-8
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发表时间：
2018-03
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影响因子：
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通讯作者：
Khokon Hossen;X. Ren;Enliang Wang;S. Kumar;A. Dorn
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文献类型：
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作者：
Khokon Hossen;X. Ren;Enliang Wang;S. Kumar;A. Dorn
本文研究了低能（E0= 38和67 eV）电子碰撞引起的四氟甲烷（CF 4）分子的电离和碎裂。我们使用反应显微镜结合脉冲光电子发射电子束进行我们的实验研究。两个出射电子（能量E1，E2）和一个碎片离子的动量矢量被检测到在三重符合（e，2 e+离子）。解离后，观察到的片段产物为CF 3+、CF 2+、CF+、F+和C+。对于CF ~（3+）和CF ~（2+）通道，我们测量了电离轨道结合能、带电碎片的动能以及碎片结合能和动能之间的二维关联图。从BE和KE光谱中，我们得出哪些分子轨道对CF 4的特定碎裂通道有贡献的结论。我们还测量了总的电离截面为形成的CF 3+和CF 2+离子作为射弹能量的函数。我们比较我们的结果与早期的实验和计算的电子碰撞和光电离。对CF 3+形成的贡献主要来自4 t2轨道的电离，而CF2+主要是在3 t2轨道电离后形成的。我们还观察到（4a 1）− 1态对CF 3+通道的微弱贡献。图形摘要
AbstractWe study ionization and fragmentation of tetrafluoromethane (CF4) molecule induced by electron impact at low energies (E0= 38 and 67 eV). We use a reaction microscope combined with a pulsed photoemission electron beam for our experimental investigation. The momentum vectors of the two outgoing electrons (energiesE1,E2) and one fragment ion are detected in triple coincidence (e, 2e+ ion). After dissociation, the fragment products observed are CF3+, CF2+, CF+, F+and C+. For CF3+and CF2+channels, we measure the ionized orbitals binding energies, the kinetic energy (KE) of the charged fragments and the two-dimensional (2D) correlation map between binding energy (BE) and KE of the fragments. From the BE and KE spectra, we conclude which molecular orbitals contribute to particular fragmentation channels of CF4. We also measure the total ionization cross section for the formation of CF3+and CF2+ions as function of projectile energy. We compare our results with earlier experiments and calculations for electron-impact and photoionization. The major contribution to CF3+formation originates from ionization of the 4t2orbital while CF2+is mainly formed after 3t2orbital ionization. We also observe a weak contribution of the (4a1)−1state for the channel CF3+.Graphical abstract