Absolute cross sections for electron-impact single ionization ofNeq+(q=2,4–6) ions

Abstract

Absolute total cross sections for electron-impact single ionization of Ne qϩ (qϭ2,4-6͒ ions have been measured using a crossed-beams technique from below the ground-state ionization threshold to 800 eV with typical total uncertainties near the peak of the cross sections ranging from 9% for Ne 2ϩ to 13% for Ne 6ϩ . Details of the apparatus and experimental procedures used in this study are presented along with a discussion of the experimental uncertainties. The measured cross sections for all four ions are dominated by direct ionization and are in excellent agreement with the Lotz semiempirical formula. Ionization rate coefficients and fitting parameters calculated from the measured cross sections are also reported. ͓S1050-2947͑96͒03008-9͔PACS number͑s͒: 34.80.Kw

Applicability of Vaisburd and Evdokimov Model to Ionic Targets

“…The values of the parameters in formula (2.4) have been obtained for the species, from the available experimental data using the least-squares method. ; Gregory et al [18], Donets and Ovsyannikov [13] for Ne 3+ , Bannister [17], Duponchelle et al [19] for Ne 4+ , Donets and Ovsyannikov [13], Bannister [16] and Duponchelle et al [19] for Ne 5+ , Donets and Ovsyannikov [13], Bannister [17] and Duponchelle et al [19] for Ne 6+ , Donets and Ovsyannikov [13], Defrance et al [20] and Duponchelle et al [19] for Ne 7+ , Donets and Ovsyannikov [13] and Duponchelle et al [19] for Ne 8+ , Donets and Ovsyannikov [13] for Ne 9+ .…”

Atomic data for x-ray astrophysics

“…It is apparent that there are multiple measurements for many ionic species, Bannister (1996) ORNL and that there is little overlap between the adopted datasets used by various compilations. This is a manifestation of the fact that the ionization database needs to be thoroughly reexamined because different data bases give different rate coefficients (Savin, 2005).…”

“…This is due to the remaining uncertainties with regard to the applicability of experimental results to low density environments, as well as convenience. Experimental results such as those of Stenke (1999) and Bannister (1996), in which the beam composition can be thoroughly characterized provide a hopeful step in this direction. Excitation Autoionization Excitation-autoionization (EA) is a process in which an ion is collisionally excited to a multiply excited level which then autoionizes.…”

Electron capture byNe3+ions from atomic hydrogen

“…[20]). In order to investigate the fraction of metastables in the Ne 3+ ion beam produced by the ORNL ECR source, the beam, under similar ion source conditions, was directed to the crossed-beam apparatus [21,22] to measure electron-impact ionization. The measured ionization cross section (see Fig.…”