Abstract
Absolute cross section measurements for double ionization of and ions by electron impact are reported. The animated crossed beams method has been employed in the energy range from ionization threshold to approximately 2.5 keV. Present results are found to be smaller than the experimental result of Steidl et al (1995 Proc. 19th Int. Conf. Physics of Electronic and Atomic Collisions (Whistler) ed J B A Mitchell et al p 564). The role of slow positive ions trapped in the electron beam could explain the observed discrepancy. The study of double ionization processes along the fluorine isoelectronic sequence (for , and ions) shows that the results for multiply charged ions are strongly lower than predicted by classical scaling. A systematic threshold energy shift is observed in the sequence and, for , the position of the cross section maximum is found to be at an unusually high energy. The autoionizing 1P state belonging to the configuration of atomic oxygen is clearly seen to contribute to the signal above 23.7 eV. Other autoionizing states are also seen to play a role around the K-shell ionization threshold. The Bethe-plot of present data shows that the high energy behaviour of cross sections is dominated by the , term for , while it is dominated by the logarithmic term for .
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of Physics B: Atomic, Molecular and Optical Physics
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
