Electron Attachment and Detachment Processes in Electronegative Gases

Christophorou, L. G.

doi:10.1002/ctpp.19870270402

Cited by 38 publications

(4 citation statements)

References 147 publications

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“…It has to be stressed that the normalization procedure (35) can only be carried out in a reliable way if the anion yield function is obtained at sufficiently narrow electron energy width and down to sufficiently low energies. We also emphasize that the gas temperature is an important parameter since attachment cross-sections may depend very strongly on the rovibrational distribution of the molecules (O'Malley, 1967;Chantry, 1969;Massey, 1976;Christophorou, 1987;Smith and Sˇpanel, 1994;Hahndorf and Illenberger, 1997).…”

Section: Measurement Of Cross-sections For Electron Attachmentmentioning

confidence: 99%

Resonance and Threshold Phenomena in Low-Energy Electron Collisions with Molecules and Clusters

2004

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Section: Measurement Of Cross-sections For Electron Attachmentmentioning

confidence: 99%

Resonance and Threshold Phenomena in Low-Energy Electron Collisions with Molecules and Clusters

2004

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“…By using the measured EEDF, the positive ion flux data and the available cross-section data in [51][52][53][54][55][56][57][58], we estimate the number density of F − for a set of operating conditions. The production kinetics of F − may be approximated by the following equation.…”

Section: F − Number Densitymentioning

confidence: 99%

Mass spectrometric measurements in inductively coupled CF₄/Ar plasmas

Rao

Sharma

Meyyappan

2002

Plasma Sources Sci. Technol.

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Positive ion fluxes, mean ion energies and ion energy distribution functions in low pressure CF 4 /Ar plasmas have been measured. The experiments were conducted in a Gaseous Electronics Conference cell using an inductively coupled plasma device powered by a 13.56 MHz radiofrequency (rf) power source. The measurements were made at 200 and 300 W of input rf power and at 10, 20, 30 and 50 mTorr gas pressures for three gas mixtures: (i) 20% CF 4 : 80% Ar, (ii) 50% CF 4 : 50% Ar and (iii) 80% CF 4 : 20% Ar. A Langmuir probe was also used to measure plasma parameters such as n e , n + i and electron energy distribution functions (EEDF) which were subsequently used to reconcile the mass spectrometer data. CF + 3 is the most dominant fluorocarbon ion product of the plasma, followed by CF + 2 and CF + . Ar + is also detected in significant amounts with its relative flux increasing with the increase in Ar content in the gas mixture. Significant amounts of etch products, SiF +x /COF + x (x = 0-3), of the quartz window were also detected. The fluorocarbon ions are produced by direct electron impact and by ion-molecule reactions between Ar + and CF 4 as well as between CF + 3 and CF 4 . However, the concentrations of CF + 2 and CF + are much larger than that which can be possibly produced from these two processes. The available cross-section data suggest that the direct electron impact ionization of the fragment neutrals and negative ion production by electron attachment may be responsible for the increase in the concentrations of the minor ions. F − densities, estimated by using the measured EEDF and positive ion flux data and the available cross-section data, agree well with the published experimental data.

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“…Alpha particles emitted by the Polonium ionize the N2 carrier gas creating secondary electrons that are rapidly thermalized. SF6 rapidly attaches low energy electrons to form SF6-, SF•-, and F- [Christophorou, 1987], all of which react with SiF4 at the collision rate to form SiFt- [Huey and Lovejoy, 1996]. The residence time in the ion source (-30 ms) is sufficient so that the ion-molecule chemistry is driven to completion which insures that SiFt-is by far the dominant ion produced with a mass of <200 amu.…”

Section: Ion Sourcementioning

confidence: 99%

Fast time response measurements of HNO₃ in air with a chemical ionization mass spectrometer

Huey¹,

Dunlea²,

Lovejoy³

et al. 1998

J. Geophys. Res.

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Abstract. A chemical ionization mass spectrometer has been developed for fast time response measurements of HNO3 in ambient air. The apparatus was characterized in an informal intercomparison campaign at Green Mountain Mesa in Boulder, Colorado. Nitric acid was measured over a wide range of meteorological conditions. Detection limits of less than ! 5 pptv for a 1 s integration period were routinely obtained. The apparatus was sufficiently sensitive to measure ambient levels of HNO3 for all conditions except for periods of fog or heavy precipitation when HNO3 mixing ratios were less than 10 pptv.

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Electron Attachment and Detachment Processes in Electronegative Gases

Abstract: Selected results of recent studies on electron attachment (especially to excited molecules) and detachment processes in electronegative gases are presented and discussed and their relevance to modern technologies is indicated.

Cited by 38 publications

References 147 publications

Resonance and Threshold Phenomena in Low-Energy Electron Collisions with Molecules and Clusters

Resonance and Threshold Phenomena in Low-Energy Electron Collisions with Molecules and Clusters

Mass spectrometric measurements in inductively coupled CF₄/Ar plasmas

Fast time response measurements of HNO₃ in air with a chemical ionization mass spectrometer

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Electron Attachment and Detachment Processes in Electronegative Gases

Abstract: Selected results of recent studies on electron attachment (especially to excited molecules) and detachment processes in electronegative gases are presented and discussed and their relevance to modern technologies is indicated.

Cited by 38 publications

References 147 publications

Resonance and Threshold Phenomena in Low-Energy Electron Collisions with Molecules and Clusters

Resonance and Threshold Phenomena in Low-Energy Electron Collisions with Molecules and Clusters

Mass spectrometric measurements in inductively coupled CF4/Ar plasmas

Fast time response measurements of HNO3 in air with a chemical ionization mass spectrometer

Contact Info

Product

Resources

About

Mass spectrometric measurements in inductively coupled CF₄/Ar plasmas

Fast time response measurements of HNO₃ in air with a chemical ionization mass spectrometer