A measurement of the cross section for electron impact ionisation of singly charged tungsten ions
A measurement of the cross section for electron impact ionisation of singly charged tungsten ions
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单电荷钨离子电子碰撞电离截面的测量
DOI：
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发表时间：
1984
期刊：
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通讯作者：
M. Harrison
中科院分区：
文献类型：
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作者：
R. Montague;M. Harrison
交叉离子和电子束技术已被用来进行绝对测量的横截面的电离过程e+W+到2 e +W2+的能量范围从低于阈值高达750 eV。复合随机和系统误差估计为小于约5%的能量超过18 eV。W+离子可能主要处于6D基态，但在4D亚稳态中具有显著的分数。其他亚稳离子可能占总数的百分之几。将目前的数据与McGuire的玻恩模型进行比较，同时考虑了6s外层电子和5d内层电子，结果显示在50 eV以上的能量下，两者的吻合度相当好，但该理论严重低估了较低能量下的截面。测量到的基态离子的电离阈值为16.1+或-1.0 eV，而Finkelnburg和Humbach（1955年）在研究屏蔽常数时给出的阈值为17.7 eV。没有其他已知的电离阈值测量。
The crossed ion and electron beams technique has been used to make an absolute measurement of the cross section for the ionisation process e+W+ to 2e+W2+ at energies ranging from below threshold up to 750 eV. The compounded random and systematic errors are estimated to be less than about 5% at energies in excess of 18 eV. The W+ ions are probably mainly in the 6D ground state but with a significant fraction in the 4D metastable state. Other metastable ions may account for a few per cent of the total. Comparison of the present data with the scaled Born prediction of McGuire taking into account both 6s outer electrons and 5d inner-shell electrons shows quite good agreement above about 50 eV, but the theory seriously underestimates the cross section at lower energies. The measured ionisation threshold for the ground-state ion is 16.1+or-1.0 eV, compared with the 17.7 eV given by Finkelnburg and Humbach (1955) from a study of screening constants. There are no other known measurements of the ionisation threshold.