Three-dimensional density profiles of argon metastable atoms in a direct current glow discharge: experimental study and comparison with calculations

Bogaerts, Annemie; Guenard, Robert D.; Smith, Benjamin W.; Winefordner, J. D.; Harrison, W. W.; Gijbels, R.

doi:10.1016/s0584-8547(96)01578-9

Cited by 44 publications

(23 citation statements)

References 22 publications

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“…A similar second maximum appeared sometimes in our modeling results (e.g. [52,53]) depending on the discharge conditions and cell geometry. The value of the maximum in the experimental density profiles of Ferreira et al [77] was also of the order of 10 13 cm −3 , which is in excellent agreement with the results of our calculations.…”

Section: Densities and Level Populationssupporting

confidence: 82%

Numerical Modeling of Analytical Glow Discharges

Bogaerts

Gijbels

2002

Glow Discharge Plasmas in Analytical Spectroscopy

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Section: Densities and Level Populationssupporting

confidence: 82%

Numerical Modeling of Analytical Glow Discharges

Bogaerts

Gijbels

2002

Glow Discharge Plasmas in Analytical Spectroscopy

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“…The results of these calculations and models have greatly enhanced our understanding of the properties of the GD source, resulting in greater insight into the major processes that occur in the glow discharge for the analytical glow discharge community. Bogaerts et al [54][55][56] compared experimentally observed line intensities and their dependence on the excitation voltage to results from the model used in their calculation. Although the model reproduced the general trends, a detailed understanding of the observed dependence of the emission yield on plasma parameters has not yet been achieved.…”

Section: Discussion and Interpretationmentioning

confidence: 99%

“…In recent years, it has been discovered that another type of IEC effect, linked primarily to the element hydrogen, can actually affect the EYs and therefore the quantification to a significant extent [54,55]. It has been shown that the EYs of spectral lines from other elements can be dramatically affected even by very minute concentrations (a few 100 ppm) of hydrogen in the plasma.…”

Section: The Hydrogen Effectmentioning

confidence: 99%

“…The hydrogen can originate from the sample itself, contamination due to adsorbed water and pumping oil inside the source, or small vacuum leaks. Both enhancement and suppression effects can be observed for a particular element, depending on the emission line used, showing that the excitation probabilities of excited levels are affected, and it is not "plasma chemical" reactions at work [54]. In general terms, these effects can be described as a change in the plasma excitation temperature, but the actual mechanisms responsible for this effect are complex [56].…”

Section: The Hydrogen Effectmentioning

confidence: 99%

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The concept of constant emission yield in GDOES

Bengtson¹,

Nelis

2006

Anal Bioanal Chem

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This review paper describes the evolution of the quantification procedure for compositional depth profiling (CDP) in glow discharge optical emission spectrometry (GD-OES), based on the constant emission yield concept. The concept of emission yield (EY) is defined and ways of measuring it experimentally are discussed. The history of the development of quantitative CDP is reviewed, which shows that all of the different approaches depend on the assumption that the EY is essentially a matrix-independent quantity. Particular emphasis is placed on the dependence of the EY on the plasma parameters of current, voltage, power and pressure. In short, impedance changes (current voltage) can significantly affect the emission yield and should either be corrected mathematically or the impedance should be kept constant by pressure regulation in order to obtain reliable results from GDOES CDP. On the other hand, the effect of varying the pressure on the emission yield can be considered to be minor within the limits of practical operating conditions for most CDP applications. It is worth, however, bearing in mind that varying the discharge pressure has a significant effect on the plasma processes, and does affect the emission yield when these variations are large. The experimental results obtained for the emission yield are related to the results from theoretical model calculations published on the subject.

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“…12 Since then many papers have been published, where the Ar m metastables are being studied either experimentally ͑using atomic absorption spectroscopy, [13][14][15][16] plasmainduced emission spectroscopy, 17 laser-induced fluorescence, 18 etc.͒ as well as by numerical models ͑where the transport of metastable atoms is described by continuity equations, yielding the metastable density͒. [19][20][21] The population of Ar m metastable atoms was studied, experimentally and with the use of balance equations, in various kinds of plasmas including afterglow, 22,23 dc, 24 rf, [25][26][27] and helicon 15 discharges. Also some studies have been performed with respect to the role of metastables in the glow discharge with formation of a positive column ͑PC͒.…”

Section: Introductionmentioning

confidence: 99%

Study of the Ar metastable atom population in a hollow cathode discharge by means of a hybrid model and spectrometric measurements

Baguer

Bogaerts

Gijbels

et al. 2005

Journal of Applied Physics

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The role of the metastable Ar atoms in a 1-cm-diameter cylindrical hollow cathode discharge ͑HCD͒ is studied self-consistently based on a hybrid model and experimental measurements in the pressure range of 0.3-1 Torr and currents of 1-10 mA. The model comprises submodels based on the principles of Monte Carlo and fluid simulations. The Monte Carlo model describes the movement of the fast electrons, fast Ar and Cu atoms, and fast Ar + and Cu + ions as particles, while in the fluid model, the slow electrons, Ar + , Cu + ions, Cu, and Ar metastable atoms are treated as a continuum. The population of the two metastable states within the 3p 5 4s configuration ͑ 3 P 2 and 3 P 0 ͒ were combined into one collective level, for which the continuity equation was written. Typical calculation results are, among others, the two-dimensional profiles of the production and the loss rates of Ar metastable atoms, as well as the metastable atom densities and fluxes throughout the complete HCD. Moreover, the calculated radial profiles ͑averaged over the axial direction͒ of the Ar metastable atom density are compared with experimental radial density profiles recorded by laser absorption spectroscopy. The relative importance of the different processes determining the Ar metastable population is analyzed, as well as the influence of pressure and voltage on them. Experimental results evidence the presence of the metastable atom production source at the cathode surface, probably originating from fast Ar + ions and Ar atoms impinging on it. Comparison between experimental and calculated Ar metastable atom densities shows a good agreement at low pressures, but at 1 Torr the calculated values differ by a factor of 2 from the measured ones. Several possible explanations for this discrepancy are discussed.

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Three-dimensional density profiles of argon metastable atoms in a direct current glow discharge: experimental study and comparison with calculations

Cited by 44 publications

References 22 publications

Numerical Modeling of Analytical Glow Discharges

Numerical Modeling of Analytical Glow Discharges

The concept of constant emission yield in GDOES

Study of the Ar metastable atom population in a hollow cathode discharge by means of a hybrid model and spectrometric measurements

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