Excitation behavior of chromium emission lines from a radio-frequency glow discharge plasma associated with bias current introduction (in Japanese)
BUNSEKI KAGAKU, 53 (2004) 1207-1213
Abstract
The introduction of d.c. bias current to an r.f. glow discharge plasma led to the intensity increase of particular emission lines. It was considered that the excitation mechanism was investigated based on Boltzmann plots of chromium emission lines with and without the bias-current introduction. In the case of Cr I lines, the Boltzmann plot follows a straight lines without the bias-current introduction whereas the plot bends upwards when the bias-current introduction. This effect could be explained from the fact that the excited levels having the energies of 4.2 eV and 5.8 eV were more populated compared to the excited levels of 3.3 eV through the collision with introduced electrons. On the other hand, the Boltzmann plot of Cr II lines bends downwards with no bias currents, which is caused by selective excitation of Cr ion species having the excite energies of 8 eV through the charge transfer collisions between Cr atom and Ar ion. When the bias currents were introduced, the charge transfer collisions could be less effective, leading to the straight relationship of the Boltzmann plot of Cr II lines. These effects suggested that the bias-current introduction is effective in enhancement of the intensities of not only Ni or Cr atomic emission lines but also the other atomic emission lines.
Key words: r. f. glow discharge plasma; Grimm glow lamp; enhancement of emission intensity; Boltzmann plot; chromium