Bias-current modulation technique of a radio-frequency glow discharge plasma for atomic emission analysis associated with a fast Fourier transform analyzer

Wagatsuma, Kazuaki; Urushibata, Satomi

doi:10.1016/j.microc.2009.11.007

Cited by 4 publications

(5 citation statements)

References 9 publications

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“…We have also suggested a modulation detection method for the pulsated bias current by using an FFT analyser, 9,10) where the bias current is pulsated with a square waveform and then the synchronously-pulsated component of the emission signal is detected selectively. This method is briefly reviewed here to explain the following experimental results.…”

Section: Methodsmentioning

confidence: 99%

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Determination of Minor Alloyed Elements in Steel Samples in Radio-frequency Glow Discharge Plasma Optical Emission Spectrometry Associated with Pulsed Bias-Current Modulation Technique

Urushibata

Wagatsuma

2012

ISIJ Int.

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An advanced detection method based on a modulation technique is described in radio-frequency-powered glow discharge plasma optical emission spectrometry (r.f. GD-OES). A frequency-sensitive separation using a fast Fourier transform (FFT) analyser, where a pulsated bias-current was introduced into an r.f. GD plasma, was available for improving the limit of determination for the atomic emission analysis. The FFT analyser has an ability to disperse signal components by frequency, and it is thus employed to select the component of a particular frequency. A dc bias current introduced into the GD plasma can enhance the emission intensities of analyte species greatly, and furthermore, it can be easily pulsated to modulate the emission intensities from the plasma. The modulated emission signal was selectively detected with the FFT analyser, with removing any noise components from the overall signal. The duty ratio of the pulsed bias current largely affected the amplitude of the FFT frequency components, because the pulse waveform comprised sine-function components having frequencies integral-times as much as the fundamental frequency, whose contribution coefficients depended on the duty ratio. This detection method was applied to the determination of vanadium and molybdenum in low-alloyed steel samples. The detection limits were obtained to be 6.2 × 10 -3 mass% V and 2.0 × 10 -3 mass% Mo in low-alloyed steel samples.

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Section: Methodsmentioning

confidence: 99%

“…10) High-purity argon (>99.999%) was introduced as the plasma gas after evacuating the chamber to below 10 Pa. The plasma gas continued to flow during a measurement while maintaining a chamber pressure of 2.7 × 10 2 Pa. An iron -aluminium alloy sample containing 0.46 mass% Al was prepared to estimate the characteristics of the r.f.…”

Section: )mentioning

confidence: 99%

Determination of Minor Alloyed Elements in Steel Samples in Radio-frequency Glow Discharge Plasma Optical Emission Spectrometry Associated with Pulsed Bias-Current Modulation Technique

Urushibata

Wagatsuma

2012

ISIJ Int.

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“…This new assembly allowed submicrometer layer analysis for depth profiling of thin layered structures, such as photovoltaic films. For GD-OES, Wagatsuma and Urushibata reported on a fast Fourier transform (FFT) analyzer to estimate the emission intensity from an rf GD . As this analyzer can disperse the components by frequency from an overall signal, it works as a selective detector in modulation spectroscopy.…”

Section: Glow Discharge Optical Emission and Mass Spectrometrymentioning

confidence: 99%

“…A dc bias current was introduced and could be pulsated to modulate the emission intensities, and subsequently the modulated component was selectively detected with the FFT analyzer. In this way, the data precision was greatly improved …”

Section: Glow Discharge Optical Emission and Mass Spectrometrymentioning

confidence: 99%

Atomic Spectroscopy

2012

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“…8 More recently, we reported that a pulsation of the bias current enabled the emission intensity to be measured with better signal-to-noise and signal-to-background ratios because a modulation detection technique using a fast Fourier transform analyzer could be applied to detect the emission signal selectively. 9,10 For optimization of the measuring parameters in this method, it is important to understand how the DC current affects the excitation process of emission spectra from the RF glow discharge plasma. Our previous paper indicated that, when many nickel emission lines were measured with and without the bias-current introduction, the bias current changed their emission intensities in different manners that were determined principally by their excitation energies.…”

Section: Introductionmentioning

confidence: 99%

Excitation Processes in Introduction of Bias Current to a Radio-frequency Glow Discharge Plasma Evaluated from Boltzmann Plots of Iron Atomic and Ionic Spectral Lines

2012

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A DC current, which was driven by the self-bias voltage, could be conducted in a radio-frequency-powered glow discharge plasma by connecting a low-pass filter circuit and a load resistor with the discharge tube. This current enhanced the intensity of emission spectra from the plasma largely. The intensities of iron atomic lines increased 35 -50 times, whereas the sputtering rate was not changed by the current introduction. Boltzmann plots for iron atomic (Fe I) and ionic lines (Fe II) were investigated when the bias current was conducted, so that the excitation process relating to the intensity increase could be clarified. While the excitation temperature of the Fe I lines was slightly changed (3000 -3600 K), that of the Fe II lines was drastically reduced from 7600 to 4300 K, which was close to the temperature of the Fe I lines at higher bias currents. Therefore, the plasma was changed towards an LTE condition so that both the Fe I and the Fe II lines could be excited through a common major process. The bias-current enhanced the density of electrons enabling low-lying excited energy levels (3 -5 eV) of iron atom/ion to be much more populated, and they became the major colliding partners for the excitation of these iron species.

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Bias-current modulation technique of a radio-frequency glow discharge plasma for atomic emission analysis associated with a fast Fourier transform analyzer

Cited by 4 publications

References 9 publications

Determination of Minor Alloyed Elements in Steel Samples in Radio-frequency Glow Discharge Plasma Optical Emission Spectrometry Associated with Pulsed Bias-Current Modulation Technique

Determination of Minor Alloyed Elements in Steel Samples in Radio-frequency Glow Discharge Plasma Optical Emission Spectrometry Associated with Pulsed Bias-Current Modulation Technique

Atomic Spectroscopy

Excitation Processes in Introduction of Bias Current to a Radio-frequency Glow Discharge Plasma Evaluated from Boltzmann Plots of Iron Atomic and Ionic Spectral Lines

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