TY - JOUR
T1 - 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
AU - Wagatsuma, Kazuaki
AU - Oka, Ryuichiro
AU - Urushibata, Satomi
PY - 2012
Y1 - 2012
N2 - 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.
AB - 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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U2 - 10.2116/analsci.28.759
DO - 10.2116/analsci.28.759
M3 - Article
AN - SCOPUS:84867378350
VL - 28
SP - 759
EP - 765
JO - Analytical Sciences
JF - Analytical Sciences
SN - 0910-6340
IS - 8
ER -