Electron-impact detachment from negative ions

Jiang²,

J. Phys. B: At. Mol. Opt. Phys.

1996

Abstract. Cross sections of electron-impact detachment of negative ions and of mutual neutralization between positive and negative ions are calculated using a model based on the semiclassical theory for ion-atom collisions but modified to include Coulomb trajectory effects. It is shown that the method allows us to obtain accurate results for collisions down to low energies. The Coulomb repulsion between the electron and the negative ion accounts for the rapid decrease of detachment cross sections at low energies, and the Coulomb attraction between positive and negative ions accounts for the rapid increase of neutralization cross sections at low velocities.

Section: Detachment Cross Sectionsmentioning

confidence: 70%

“…The detachment cross sections obtained from the latter model are not in good agreement with data. The readers are referred to Vejby-Christensen et al (1996) for details of these two models.…”

Section: Detachment Cross Sectionsmentioning

confidence: 99%

Coulomb trajectory effects on electron-impact detachment of negative ions and on mutual neutralization cross sections

Jiang²,

J. Phys. B: At. Mol. Opt. Phys.

1996

J. Phys. B: At. Mol. Opt. Phys.

“…The two storage rings have similar features, and the experimental procedures differ only slightly between them. A general description of the apparatuses and procedures can be found in previous papers [7,8]. In both experiments, the ions were produced from CF 4 parent gas in a Nielsen-type ion source [9]; the CF•2 was created without a filament at high pressure (about 0.1 Torr) and with an electrical discharge of 1 kV, whereas the CF' was produced in the more standard way with a filament and low pressure (about 1 mTorr).…”

Section: Experimental Methodsmentioning

confidence: 99%

The dissociative recombination of fluorocarbon ions III: CF⁺₂and CF⁺₃

Ehlerding

Viggiano²,

Hellberg

et al. 2006

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORIMONITOR'S ACRONYM(S)AFRL/VSBXT SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution unlimited. SUPPLEMENTARY NOTESReprinted from J. Abstract Cross sections and branching ratios are presented for the dissociative recombination of the CF' and CF'3 ions with electrons. It is found that the channel producing CF + F is dominant for the reaction with CF' and the production of CF 2 + F is dominant for the reaction with CF+. The cross sections for these two ions are very similar.

J. Phys. D: Appl. Phys.

“…For impact ionization [48], dissociative attachment [52], and impact detachment [53,54,55] we used empirical cross sections throughout, putting, in the case of impact detachment a higher confidence level to more recent data [55], whereas for dissociative recombination, ion-ion neutralization, and detachment on neutrals we combined empirical data with analytical models.…”

Section: Electron and Ion Production And Loss Reactionsmentioning

confidence: 99%

“…The collisions included in our model are discussed in Section III. Where necessary, we combine measured cross sections [48,49,50,51,52,53,54,55,56,57,58,59,60] with model cross sections [61,62,63,64,65] to characterize collisions and fix the free parameters through a comparison with experimental data. In Section IV we show that once the parameters are fixed, good agreement between simulation and experiment can be achieved in the bulk of the discharge.…”

Section: Introductionmentioning

confidence: 99%

Radio-frequency discharges in oxygen: I. Particle-based modelling

Bronold

Matyash

Tskhakaya

et al. 2007

In this series of three papers we present results from a combined experimental and theoretical, particle-based study to quantitatively describe capacitively coupled radio-frequency discharges in oxygen. The particle-in-cell Monte Carlo model on which the theoretical description is based is described in this paper. It treats space charge fields and transport processes on an equal footing with the most important plasma–chemical reactions. For given external voltage and pressure, the model determines the electric potential within the discharge and the distribution functions for electrons, negatively charged atomic oxygen and positively charged molecular oxygen. Previously used scattering and reaction cross section data are critically assessed and in some cases modified. To validate our model, we compare the densities in the bulk of the discharge with experimental data and find good agreement, indicating that essential aspects of an oxygen discharge are captured.