Absolute cross sections for electron-impact ionization of the rare-gas atoms by the fast-neutral-beam method

Wetzel, Robert C.; Baiocchi, F. A.; Hayes, Todd R.; Freund, Robert M.

doi:10.1103/physreva.35.559

Cited by 375 publications

(222 citation statements)

References 53 publications

Supporting

Mentioning

197

Contrasting

Order By: Relevance

“…Experimental ionization efficiency curves published up to 1986 for atoms and molecular gases are reproduced in [145]. Measurements for 27 atoms were performed since with a crossed-beam apparatus based on the use of fast atoms and molecules rather than on thermally produced ones [146][147][148][149]. Results of earlier measurements for several additional elements are also cited in the latter reference.…”

confidence: 99%

High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

Drowart

Chatillon

Hastie

et al. 2005

Pure and Applied Chemistry

234

184

View full text Add to dashboard Cite

An assessment of high-temperature mass spectrometry and of sources of inaccuracy is made. Experimental, calculated, and estimated cross-sections for ionization of atoms and inorganic molecules typically present in high-temperature vapors are summarized. Experimental cross-sections determined for some 56 atoms are generally close to theoretically calculated values, especially when excitation–autoionization is taken into account. Absolute or relative cross-sections for formation of parent ions were measured for ca. 100 molecules. These include homonuclear diatomic and polyatomic molecules, oxides, chalcogenides, halides, and hydroxides. Additivity of atomic cross-sections supplemented by empirical corrections provides fair estimates of molecular cross-sections. Causes of uncertainty are differences in interatomic distances and in shapes of potential energy curves (surfaces) of neutral molecules and of molecular ions and tendency toward dissociative ionization in certain types of molecules. Various mass spectrometric procedures are described that render the accuracy of measured thermodynamic properties of materials largely independent of ionization cross-sections. This accuracy is comparable with that of other techniques applicable under the conditions of interest, but often only the mass spectrometric procedure is appropriate at high temperatures.

show abstract

confidence: 99%

High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

Drowart

Chatillon

Hastie

et al. 2005

Pure and Applied Chemistry

234

184

View full text Add to dashboard Cite

show abstract

“…We consider these data as the presently most reliable data set. Shah et al 30 and Wetzel et al 31 measured electron ionization cross sections and compared their results to existing literature data. Their values agree with published data within 15 %.…”

Section: Electron Collisionsmentioning

confidence: 99%

“…In this range the calculated K k was fitted according to Eqn. 6. σ k were taken from Yoon et al 29 for electron collisions with H 2 , from Shah et al 30 for electron collisions with H, and from Wetzel et al 31 for electron collisions with Ar. Yoon et al 29 compiled a collection of recommended values of cross sections for electron collisions with hydrogen molecules.…”

Section: Electron Collisionsmentioning

confidence: 99%

Ion chemistry in H2-Ar low temperature plasmas

Sode

Schwarz-Selinger

Jacob

2013

Journal of Applied Physics

View full text Add to dashboard Cite

A rate equation model is devised to study the ion composition of inductively coupled H 2 -Ar plasmas with different H 2 -Ar mixing ratios. The model is applied to calculate the ion densities n i , the wall loss probability of atomic hydrogen β H , and the electron temperature T e . The calculated n i 's of Ar + , H + , H + 2 , H + 3 and ArH + are compared with experimental results. Calculations were made for a total gas pressure of 1.0 Pa. The production and loss channels of all ions are presented and discussed in detail. With the production and loss rates the density dependence of each ion on the plasma parameters are explained. It is shown that the primary ions H + 2 and Ar + which are produced by ionization of the background gas by electron collisions are effectively converted into H + 3 and ArH + . The high density of ArH + and Ar + is attributed to the low loss to the walls compared to hydrogen ions. It is shown that the H + /H + 2 density ratio is strongly correlated to the H/H 2 density ratio. The dissociation degree is around 1.7 %. From matching the calculated to the measured atomic hydrogen density n H the wall loss probability of atomic hydrogen on stainless steel β H was determined to be β H = 0.24. The model results were compared with recently published experimental results. The calculated and experimentally obtained data are in fair agreement.

show abstract

“…Dividing the signal S PM (M k ) measured for this species by its neutral pressure p k in the vessel and the partial cross section for electron-impact ionization σ gas (eV e ) at the used electron energy eV e = 70 eV (σ gas is taken from Ref. 41,42 ) one obtains a signal that depends on the ion mass only 43 . For species were several isotopes are present the natural abundance α k of the detected ion needs to be additionally taken into account.…”

Section: Mass-dependent Transmissionmentioning

confidence: 99%

Quantitative determination of mass-resolved ion densities in H2-Ar inductively coupled radio frequency plasmas

Sode

Schwarz-Selinger

Jacob

2013

Journal of Applied Physics

View full text Add to dashboard Cite

Inductively coupled H 2 -Ar plasmas are characterized by an energy-dispersive mass spectrometer (plasma monitor), a retarding field analyzer, optical emission spectroscopy and a Langmuir probe. A procedure is presented that allows determining quantitatively the absolute ion densities of Ar + , H + , H + 2 , H + 3 and ArH + from the plasma monitor raw signals. The calibration procedure considers the energy and mass-dependent transmission of the plasma monitor. It is shown that an additional diagnostic like a Langmuir probe or a retarding field analyzer is necessary to derive absolute fluxes with the plasma monitor. The conversion from fluxes into densities is based on a sheath and density profile model.Measurements were conducted for a total gas pressure of 1.0 Pa. For pure H 2 plasmas the dominant ion is H + 3 . For mixed H 2 -Ar plasmas the ArH + molecular ion is the most dominant ion species in a wide parameter range. The electron density n e is around 3 × 10 16 m −3 and the electron temperature T e decreases from 5 to 3 eV with increasing Ar content. The dissociation degree was measured by actinometry. It is around 1.7 % nearly independent on Ar content. The gas temperature, estimated by the rotational distribution of the Q-branch lines of the H 2 Fulcher-α diagonal band (v' = v" = 2) is estimated to (540±50) K.

show abstract

Absolute cross sections for electron-impact ionization of the rare-gas atoms by the fast-neutral-beam method

Cited by 375 publications

References 53 publications

High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

Ion chemistry in H2-Ar low temperature plasmas

Quantitative determination of mass-resolved ion densities in H2-Ar inductively coupled radio frequency plasmas

Contact Info

Product

Resources

About