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

Bogaerts, Annemie; Wagner, Eugene P.; Smith, Benjamin W.; Winefordner, J. D.; Pollmann, D.; Harrison, W. W.; Gijbels, R.

doi:10.1016/s0584-8547(96)01577-7

Cited by 42 publications

(36 citation statements)

References 36 publications

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“…The corresponding tantalum ion density, calculated for the same cell and under the same dc discharge conditions, is presented in Figure 6.12a [55]. We found that the tantalum ion and argon ion densities are characterized by the same relative profile, but the tantalum ion density is more than two orders of magnitude lower.…”

Section: Densities and Level Populationsmentioning

confidence: 81%

“…typical values of about 10 −4 -5 × 10 −2 were obtained [46,47,55]. To check the results of the modeling, the tantalum ion density has also been measured by LIF, and the result is shown in Figure 6.12b [55]. Calculated and experimental results qualitatively are in good agreement, but the quantitative agreement is poor.…”

Section: Densities and Level Populationsmentioning

confidence: 93%

“…possible disturbance of the plasma by the Langmuir probe, possible contamination due to deposition on this probe, approximations in the Langmuir probe theory). Figure 6.11a shows the calculated two-dimensional density profile of the sputtered cathode atoms in the case of tantalum (the reason for taking tantalum as an example is given below), for a six-way cross glow discharge cell (approximated to be cylindrically symmetrical) and dc conditions of 1000 V, 1 Torr and ca 2 mA [55]. The cathode is found at the left-hand side of the figure, whereas the other borders of the figure are anode walls.…”

Section: Densities and Level Populationsmentioning

confidence: 99%

“…Tantalum was used as the cathode material, because it has fluorescent lines which are in the suitable wavelength range of the laser available for the experiment [55]. The result of the LIF measurements is depicted in Figure 6.11b; the combined LIF + AAS experiments yielded values which were generally a factor of three lower [55].…”

Section: Densities and Level Populationsmentioning

confidence: 99%

“…Under the discharge conditions under consideration, the degree of ionization was calculated to be of the order of 10 −5 -10 −3 for argon, whereas for the sputtered atoms (tantalum, copper, etc.) typical values of about 10 −4 -5 × 10 −2 were obtained [46,47,55]. To check the results of the modeling, the tantalum ion density has also been measured by LIF, and the result is shown in Figure 6.12b [55].…”

Section: Densities and Level Populationsmentioning

confidence: 99%

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Numerical Modeling of Analytical Glow Discharges

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2002

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Section: Densities and Level Populationsmentioning

confidence: 81%

Section: Densities and Level Populationsmentioning

confidence: 93%

Section: Densities and Level Populationsmentioning

confidence: 99%

Section: Densities and Level Populationsmentioning

confidence: 99%

Section: Densities and Level Populationsmentioning

confidence: 99%

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Numerical Modeling of Analytical Glow Discharges

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2002

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Glow Discharge Optical Spectroscopy and Mass Spectrometry

Bogaerts

2016

Encyclopedia of Analytical Chemistry

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Atomic Spectroscopy Optical (atomic absorption spectroscopy, AAS; atomic emission spectroscopy, AES; atomic fluorescence spectroscopy, AFS; and optogalvanic spectroscopy) and mass spectrometric (magnetic sector, quadrupole mass analyzer, QMA; quadrupole ion trap, QIT; Fourier transform ion cyclotron resonance, FTICR; and time‐of‐flight, TOF) instrumentation are well suited for coupling to the glow discharge (GD). The GD is a relatively simple device. A potential gradient (500–1500 V) is applied between an anode and a cathode. In most cases, the sample is also the cathode. A noble gas (mostly Ar) is introduced into the discharge region before power initiation. When a potential is applied, electrons are accelerated toward the anode. As these electrons accelerate, they collide with gas atoms. A fraction of these collisions are of sufficient energy to remove an electron from a support gas atom, forming an ion. These ions are, in turn, accelerated toward the cathode. These ions impinge on the surface of the cathode, sputtering sample atoms from the surface. Sputtered atoms that do not redeposit on the surface diffuse into the excitation/ionization regions of the plasma where they can undergo excitation and/or ionization via a number of collisional processes, and the photons or ions created in this way can be detected with optical emission spectroscopy or mass spectrometry. GD sources offer a number of distinct advantages that make them well suited for specific types of analyses. These sources afford direct analysis of solid samples, thus minimizing the sample preparation required for analysis. The nature of the plasma also provides mutually exclusive atomization and excitation processes that help to minimize the matrix effects that plague so many other elemental techniques. In recent years, there is also increasing interest for using GD sources for liquid and gas analyses. In this article, first, the principles of operation of the GD plasma are reviewed, with an emphasis on how those principles relate to optical spectroscopy and mass spectrometry. Basic applications of the GD techniques are considered next. These include bulk analysis, surface analysis, and the analysis of solution and gaseous samples. The requirements necessary to obtain optical information are addressed following the analytical applications. This article focuses on the instrumentation needed to make optical measurements using the GD as an atomization/excitation source. Finally, mass spectrometric instrumentation and interfaces are addressed as they pertain to the use of a GD plasma as an ion source. GD sources provide analytically useful gas‐phase species from solid samples. These sources can be interfaced with a variety of spectroscopic and spectrometric instruments for both quantitative and qualitative analyses.

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