Effects of helium addition to an argon glow discharge plasma on emission lines of sputtered particles

Wagatsuma, Kazuaki; Hirokawa, Kichinosuke

doi:10.1021/ac00158a022

Cited by 46 publications

(15 citation statements)

References 47 publications

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“…Previous studies reported on a reduction in the sputtering rate caused by He addition to an Ar glow discharge plasma. 16,17 The intensity change of the Fe I line seems to correspond to the variation in the sputtering rate, because the intensity of the Fe I line having a smaller excitation energy (3.43 eV) 4 can be varied principally by the sample atom density in the plasma. However, the intensity of the As I line having a larger excitation energy becomes elevated up to a He pressure of 400 Pa even if the number of sample atoms ejected into the plasma is reduced.…”

Section: Resultsmentioning

confidence: 99%

“…This is probably because the sputtering rate as well as the discharge current is reduced by adding He to the Ar glow discharge plasmas. 16 In the mixed gas plasma, the SBR is greatly improved along with increasing the discharge voltage. At higher discharge voltages, the plasma with an Ar-He mixed gas could give a better analytical performance in the As determination.…”

Section: Resultsmentioning

confidence: 99%

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Direct Determination of Arsenic in Steel by Glow Discharge Optical Emission vSpectrometry with Argon-Helium Mixed Gas

Wagatsuma

2003

ANAL. SCI.

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To protect the environment from increasing scrapped materials, drastic changes in the processes for materials production are required. Material recycling must be considered in the production system to greatly help much in saving both energy and resources in the massive initial mining, processing, transportation, and smelting operations. One major concern regarding the recycling process is the inclusion of impurity elements, which are called tramp elements in the steel-making industry. These tramp elements are generally difficult to remove in the refining process, and degrade the quality of the produced steels. Arsenic is a tramp element because it is possibly included in the recycling process of steel material, and degrades the mechanical property of commercial steels. Therefore, a rapid determination of As is needed so that quality control can be strictly performed for utilizing recycled materials.Glow discharge optical emission spectrometry (GD-OES) is an analytical method for the direct analysis of solid samples, and a powerful tool for the quality control of various manufactured materials. [1][2][3] Because the content of the tramp elements is generally small (several 100 ppm down to 1 ppm), the detection sensitivity of GD-OES should be improved for analytical applications to tramp elements. In this study, GD-OES with an Ar-He mixed gas plasma was applied to the determination of As in steel samples to better the detection limit by enhancing the intensity of the As emission lines as well as by decreasing the background intensity. In GD-OES, Ar is commonly employed as the plasma gas due to the low runningcost as well as good performance as an emission source. However, changing the plasma gas could be a possible option to improve the detection sensitivity. Helium has a higher ionization potential (24.48 eV) 4 compared to argon (15.76 eV), 4 thus leading to a lower density of charged particles in the plasma. It also has a lower sputtering yield. 5,6 Thus, helium would not be a suitable plasma gas for GD-OES because the sputtering rate would be too low. However, argon-helium mixed gas plasmas are interesting. . Atoms in such metastable levels have relatively long lifetimes, especially at low pressures, and thus can cause excitation of the sample atoms through various collisions. In addition, in an Ar-He mixed gas plasma, the He metastables could principally contribute to the excitations of species having larger excitation energies. 7,11 Since it is considered that the helium metastables have larger internal energies, sample atoms requiring higher excitation energies may be more readily excited by He than by Ar, thus leading to an intensity increase in the emission lines. A few studies on an analytical application using Ar-He mixed gases were presented. The determination of C has been reported, indicating that the detection sensitivity obtained with Ar-He mixed gas plasma was three-times improved compared with Ar alone. 11 Like carbon, the emission transitions of As require a relatively large excitation energy, wh...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Direct Determination of Arsenic in Steel by Glow Discharge Optical Emission vSpectrometry with Argon-Helium Mixed Gas

Wagatsuma

2003

ANAL. SCI.

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“…The emission intensity of iron decreases with the helium pressure added, which could be explained from a decrease in the sputtering rate caused by the addition of helium. 18,19) In fact, the sputtering rates were measured to be 1.0ϫ10 Ϫ4 g cm Ϫ2 min Ϫ1 for 530-Pa argon alone and 0.51ϫ10 Ϫ4 g cm Ϫ2 min Ϫ1 for 530-Pa argon and 530-Pa helium mixed gas. It is likely to consider that the intensities of the iron line having smaller excitation energy (3.43 eV) 6) correspond to the sample atom density in the plasma more closely.…”

Section: Resultsmentioning

confidence: 99%

“…This is probably because the sputtering rate as well as the discharge current is reduced by adding helium to argon glow discharge plasmas. 18) In the mixed gas plasma, the SBR is much improved along with increasing discharge voltage. It is expected that, at higher discharge voltages, the plasma with argon-helium mixtures gives better analytical performance in the carbon determination.…”

Section: Resultsmentioning

confidence: 99%

Advantage of Argon-helium Mixed Gas Plasmas for Carbon Determination in Glow Discharge Optical Emission Spectrometry.

Wagatsuma

2000

ISIJ International

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“…Whereas argon is usually used in conventional GD-OES, various plasma gases and their mixtures have been thus investigated as alternative plasma gases. [8][9][10][11][12][13] Their observed spectrum patterns were different from each other, in which the difference is not only in their relative intensities but in the kind of emission lines that can be excited; therefore, one should select optimum analytical lines for each plasma gas employed. We discussed the line selection of copper in GD-OES when using argon and neon as the plasma gas, indicating that different emission lines should be employed for their emission analysis.…”

Section: Introductionmentioning

confidence: 99%

Selection of Optimum Analytical Lines for the Determination of Several Alloyed Elements in Steel Samples in Glow Discharge Optical Emission Spectrometry with Krypton and Argon

Wagatsuma

2009

ISIJ Int.

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The most sensitive emission lines for determination of cobalt, nickel, and vanadium in steel samples were investigated when krypton was employed as an alternative plasma gas in glow discharge optical emission spectrometry. A thorough survey in the emission spectra indicated that more sensitive ionic lines of nickel as well as cobalt, which were free from spectral interference from iron, could be found when using krypton gas instead of argon gas; therefore, the krypton plasma was recommended in the determination of nickel and cobalt in iron-matrix alloy samples. However, the argon plasma yielded more intense ionic lines of vanadium suitable for the vanadium determination in iron-matrix alloy samples. These phenomena could be explained by resonance energy-transfer collisions with the plasma gases which selectively populate different excited levels of these ions between the krypton and the argon plasmas.KEY WORDS: glow discharge optical emission spectrometry; sensitive analytical line; krypton plasma; nickel; cobalt; vanadium.particular emission line and a plasma gas could improve the detection sensitivity in GD-OES, in the case where this resonance condition is fulfilled for the corresponding excited energy level. In this paper, we represent optimum analytical lines for determination of cobalt, nickel, and vanadium in steel samples when krypton is employed as the plasma gas instead of argon. ExperimentalThe Grimm-style glow discharge lamp 18) and the spectrometer system employed 19) have been described in our previous papers. The excitation source was in-house made according to the original model by Grimm. 20) Table 1 summarizes the apparatus and the experimental conditions in detail.Iron-cobalt, iron-nickel, and iron-vanadium binary alloy samples (FXS standard reference materials for X-ray fluorescence analysis, the Iron and Steel Institute of Japan) were employed. Their compositions are 0.52 and 1.06 mass% Ni, 0.50 and 1.02 mass% Co, and 0.49, 1.00, and 2.04 mass% V, respectively. A pure iron plate (99.8 %, purity), a pure nickel plate (99.9 %), a pure cobalt block (99.9 %), and a pure vanadium plate (99.99 %) were also prepared as reference samples. It was polished with waterproof emery papers and then rinsed with ethanol. Before the measurement, pre-discharge was carried out for 5-10 min to remove the surface contaminants. High-purity argon (99.99995 %) or krypton (99.9995 %) was employed as the plasma gas. The pressure of the plasma gas was measured at the vacuum port of the glow lamp with a Prani vacuum gauge, whose readings had been corrected for each gas. Results and DiscussionWe have already conducted a comparative measurement of Ni II emission lines when krypton and argon are employed in GD-OES, based on a discussion on the excitation mechanism, and published a wavelength table for the observed Ni II lines.15) The major Ni II lines are assigned to the 3d 8 4p-3d 8 4s (3d 9 ) transition, whose excitation energies range from 6.39 to 9.39 eV.21) Among them, particular Ni II lines having an excitation energy...

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Effects of helium addition to an argon glow discharge plasma on emission lines of sputtered particles

Cited by 46 publications

References 47 publications

Direct Determination of Arsenic in Steel by Glow Discharge Optical Emission vSpectrometry with Argon-Helium Mixed Gas

Direct Determination of Arsenic in Steel by Glow Discharge Optical Emission vSpectrometry with Argon-Helium Mixed Gas

Advantage of Argon-helium Mixed Gas Plasmas for Carbon Determination in Glow Discharge Optical Emission Spectrometry.

Selection of Optimum Analytical Lines for the Determination of Several Alloyed Elements in Steel Samples in Glow Discharge Optical Emission Spectrometry with Krypton and Argon

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