Comparison of NO titration and fiber optics catalytic probes for determination of neutral oxygen atom concentration in plasmas and postglows

Mozetič, Miran; Ricard, A.; Babič, Dušan; Poberaj, I.; Levaton, Jacque; Monna, V.; Cvelbar, Uroš

doi:10.1116/1.1539082

Cited by 55 publications

(41 citation statements)

References 22 publications

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“…Our calculations are conducted for this critical electron density, so that the discharge characteristics, as well as the species densities, are obtained at the end of the plasma column. Therefore, they can be used as initial values for afterglow studies, since most of the applications rely on the early-or late-afterglow (present in a large volume reactor) of the flowing surface-wave discharge [3,20,23,41] . Take note that an axial description of a surface wave discharge can be achieved by coupling the wave and the electron power equations.…”

Section: Model Descriptionmentioning

confidence: 99%

“…) transition [3,18], and one probe method that relies on the temperature rise of a catalytic probe due to the atomic recombination on the probe surface [23,24]. For the case of a pure O 2 surface wave microwave discharge the O-atoms density was obtained by VUV absorption spectroscopy downstream the discharge by Granier et al [25] for different discharge configurations and microwave frequencies.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical insight into Ar–O₂surface-wave microwave discharges

Kutasi

Guerra²,

Sá

2010

J. Phys. D: Appl. Phys.

104

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Abstract.A zero-dimensional kinetic model has been developed to investigate the coupled electron and heavy-particle kinetics in Ar-O 2 surface-wave microwave discharges generated in long cylindrical tubes, such as those launched with a surfatron or a surfaguide. The model has been validated by comparing the calculated electron temperature and species densities with experimental data available in the literature for different discharge conditions. Systematic studies have been carried out for a surfacewave discharge generated with 2.45 GHz field frequency in a 1 cm diameter quartz tube in Ar-O 2 mixture at 0.5-3 Torr pressures, which are typical conditions found in different applications. The calculations have been performed for the critical electron density n e =3.74×10 11 cm −3 . It has been found that the sustaining electric field decreases with Ar percentage in the mixture, while the electron kinetic temperature exhibits a minimum at about 80%Ar. The charged and neutral species densities have been calculated for different mixture compositions, from pure O 2 to pure Ar, and their creation and destruction processes have been identified. The O 2 dissociation degree increases with Ar addition into O 2 and dissociation degrees as high as 60% can be achieved. Furthermore, it has been demonstrated that the dissociation degree increases with the discharge tube radius, while decreases with the atomic surface recombination of O-atoms. The density of O − negative ions is very high in the plasma, the electronegativity of the discharge can be higher than 1, depending on the discharge conditions. §

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Section: Model Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical insight into Ar–O₂surface-wave microwave discharges

Kutasi

Guerra²,

Sá

2010

J. Phys. D: Appl. Phys.

104

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“…In order to prevent a substantial drain of atoms by the probe, it should be made as small as possible. A typical dimension of a modern catalytic probe is 1 mm [26][27][28][29][30][31]. The principle of the probe operation is extremely simple: when a piece of metal is immersed into O rich atmosphere, the surface is exposed to a flux of O atoms.…”

Section: Catalytic Probesmentioning

confidence: 99%

“…The disadvantages include a poor understanding of surface recombination phenomena and sensitivity to high-frequency interferences. From the latter point of view, recently developed Fiber Optics Catalytic Probes (FOCP) have a definite advantage: as any connection is made optical, they are completely immune to stray effects caused by high frequency electromagnetic field [29][30][31]. On the other hand, the FOCPs cannot measure low densities of O atoms.…”

mentioning

confidence: 98%

An Iron Catalytic Probe for Determination of the O-atom Density in an Ar/O2 Afterglow

Mozetič

Cvelbar

Ricard

2006

Plasma Chem Plasma Process

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An iron fiber optics catalytic probe has been constructed and applied for the real-time measuring of the O-atom density in an Ar/O 2 afterglow. The recombination coefficient for the heterogeneous surface recombination of O atoms on the oxidized iron foil was measured at different temperatures between 400 and 950 K. The coefficient was found to be constant in the entire range of experimental conditions and had a value of 0.41 ± 0.12. The iron fiber optics catalytic probe has an advantage over the classical nickel fiber optics catalytic probe: the probe signal is higher for the iron probe due to a higher recombination coefficient thus causing an easier real-time monitoring of the O-atom density. The O-atom density was measured in an afterglow of microwave plasma created at different discharge powers up to 300 W, at a constant Ar flow rate of 1000 sccm/min and at different oxygen flow rates between 50 and 300 sccm/min. The O-atom density was found to be dependent on oxygen flow. At low oxygen flow rates up to 100 sccm/min, a saturation of the O-atom density was obtained at a certain discharge power, while at high oxygen flow rate the O-atom density kept increasing with the increasing power. The results were explained by gas phase and surface phenomena.

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“…Materials facing such plasmas are therefore exposed to an extremely large flux of neutral oxygen atoms, often exceeding 10 24 m ±2 s ±1 . [13] Oxygen atoms are extremely reactive and oxidize practically all materials. Since there is often no potential energy barrier, the oxidation mechanism in plasmas is completely different from classical oxidation.…”

mentioning

confidence: 99%

A Method for the Rapid Synthesis of Large Quantities of Metal Oxide Nanowires at Low Temperatures

Mozetič¹,

Cvelbar²,

Sunkara³

et al. 2005

Advanced Materials

169

103

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8, 55.8, 114.4, 122.6, 124.4, 125.8, 128.1, 128.2, 129.2, 132.0, 133.3, 142.8, 143.0, 165.2, 186.9; MS (CI): 483 (M + ). Synthesis of DCTE Compounds 7a±10a: A solution of aldehyde 3 or the appropriate ketone 4±6 (0.1 mmol) and malonodinitrile (16.5 mg, 0.25 mmol) in anhydrous dichloroethane (5 mL) was cooled in an ice bath to 0 C under nitrogen atmosphere and treated with TiCl 4 (0.1 mL, 0.91 mmol) dropwise. After stirring for 5 min, pyridine (0.2 mL) was carefully added over 20 min. The purple reaction mixture was allowed to warm to room temperature and subsequently heated at reflux for 5±10 min during which time a white precipitate formed and the color changed to pale brown. After cooling to room temperature, the solvents were evaporated under reduced pressure. The solid residue was dissolved in 15 % aqueous HCl (10 mL), the solution was extracted with chloroform (3 20 mL) and the combined organic layers were dried over MgSO 4 , filtered and concentrated in vacuum. Purification of the crude product affords DCTE 7a±10a.7a was prepared from aldehyde 3 in 93 % yield (40 mg) as an orange solid.1 H NMR spectroscopy indicated the product was pure enough to use without further purification. Mp = 102±104 C; 3, 92.6, 109.9, 112.6, 122.3, 124.4, 126.2, 129.0, 129.4, 132.5, 144.8, 145 21.7, 38.3, 93.0, 110.7, 123.2, 122.8, 126.0, 128.6, 129.4, 132.9, 142.6, 143.8, 167.4 84.5, 112.6, 113.0, 114.8, 115.3, 122.7, 123.2, 124.0, 125.9, 128.4, 129.3, 129.9, 132.2, 133.0, 143.1, 143.2, 159.5, 164.9

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Comparison of NO titration and fiber optics catalytic probes for determination of neutral oxygen atom concentration in plasmas and postglows

Cited by 55 publications

References 22 publications

Theoretical insight into Ar–O₂surface-wave microwave discharges

Theoretical insight into Ar–O₂surface-wave microwave discharges

An Iron Catalytic Probe for Determination of the O-atom Density in an Ar/O2 Afterglow

A Method for the Rapid Synthesis of Large Quantities of Metal Oxide Nanowires at Low Temperatures

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Comparison of NO titration and fiber optics catalytic probes for determination of neutral oxygen atom concentration in plasmas and postglows

Cited by 55 publications

References 22 publications

Theoretical insight into Ar–O2surface-wave microwave discharges

Theoretical insight into Ar–O2surface-wave microwave discharges

An Iron Catalytic Probe for Determination of the O-atom Density in an Ar/O2 Afterglow

A Method for the Rapid Synthesis of Large Quantities of Metal Oxide Nanowires at Low Temperatures

Contact Info

Product

Resources

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Theoretical insight into Ar–O₂surface-wave microwave discharges

Theoretical insight into Ar–O₂surface-wave microwave discharges