Kazuaki Wagatsuma

Comparative Study on Excitation Mechanism of Chromium Emission Lines in Argon Radio‐Frequency Inductively‐Coupled Plasma, Nitrogen Microwave Induced Plasma, and Argon or Nitrogen Glow Discharge Plasmas

Boltzmann plots of both atomic and ionic chromium emission lines are investigated to compare the excitation mechanisms in four different plasmas: an argon inductively‐coupled plasma (Ar‐ICP), a nitrogen high‐power microwave induced plasma (N2‐MIP), an argon glow discharge plasma (Ar‐GDP), and a nitrogen glow discharge plasma (N2‐GDP). The plots of the atomic lines and the ionic lines give both linear relationships as well as similar excitation temperatures in the case of the Ar‐ICP, the N2‐MIP, and the N2‐GDP. It implies that a thermodynamic process such as electron collision would control their excitations. However, only in the case of the ionic‐line plot in the Ar‐GDP, a departure from linear relationship is observed and the estimated excitation temperature is rather higher than that with the atomic lines, meaning that a specific excitation mechanism exists in the Ar‐GDP. A possible explanation for these results is that a charge‐transfer collision between chromium atom and argon ion plays a dominant role in exciting highly‐lying energy levels of chromium ion, especially in the Ar‐GDP.

Effect of plasma gas for spectrometric analysis of tin and zinc using low-pressure laser-induced plasma

Abstract The emission characteristics of tramp elements such as Sn and Zn in low-pressure laser-induced plasma have been examined with reference to change of the surrounding gas (Ar, Ne and He). From the pressure dependence of the intensity of Sn I 326.23-nm, Sn II 335.22-nm, Zn I 213.86-nm and Zn II 210.00-nm emission lines, it was found that Sn and Zn atoms could be excited by the collision between surrounding gas species and ablated atoms with large kinetic energy by laser irradiation. Besides the collisional excitation, resonance charge-transfer collision between Zn atoms and Ne ions proved to be effective in the selective excitation of Zn II 206.42-nm and 210.00-nm emission lines, because the emission intensity of these lines was strongly enhanced in Ne atmosphere, and the sum of the excitation energy of these lines and the ionization potential of Zn is very close to the ground-state energy of Ne ions.