Measurement of Excited Argon Atom in Glow Discharge Plasma by Diode Laser Coherent Forward Scattering Spectrometry (DL-CFS)
Measurement of Excited Argon Atom in Glow Discharge Plasma by Diode Laser Coherent Forward Scattering Spectrometry (DL-CFS)
复制标题
用二极管激光相干前向散射光谱法 (DL-CFS) 测量辉光放电等离子体中激发的氩原子
DOI：
10.2355/isijinternational.55.213
复制
发表时间：
2015
影响因子：
1.8
通讯作者：
Hideyuki Matsuta
中科院分区：
文献类型：
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作者：
Hideyuki Matsuta
当非金属原子在低压辉光放电等离子体中被激发时，可以在640-930 nm波长范围内观察到吸收跃迁，其中激光二极管是市售的。半导体激光原子吸收光谱法（DL-AAS）可以灵敏地探测这些激发态原子。由于相干前向散射（CFS）光谱法也能检测原子吸收跃迁，而二极管激光CFS光谱法比DL-AAS法更有吸引力，因此采用二极管激光相干前向散射光谱法（DL-CFS）研究了激发态氩原子在842.46 nm处的吸收跃迁。由于现有的半导体激光器的波长可调谐范围，本实验采用Ar（I）842.46nm谱线。在辉光放电等离子体中产生激发态氩原子。CFS信号强度在842.46 nm达到最大放电电流为20 mA，3托（399 Pa）的氩气和磁场为160 mT。制备氩气的校准曲线以将少量氩气混合到6托（798 Pa）的氦气中。信号强度依赖于氩数密度的4.4次方。4.4次方依赖性太大，无法用理论预测的二次依赖性来解释。当在氩等离子体中掺入少量的氮分子时，观察到CFS强度的强烈抑制。发现诸如空气的分子气体不适合于等离子体气体来激发靶原子。
When non-metallic atoms are excited in a low-pressure glow discharge plasma, absorption transitions can be observed in the 640–930 nm wavelength range where laser diodes are commercially available. These excited atoms can be sensitively probed by diode laser atomic absorption spectrometry (DL-AAS). Because an atomic absorption transition can also be detected by coherent forward scattering (CFS) spectrometry and CFS spectrometry with a diode laser has more attractive features than DL-AAS, diode laser coherent forward scattering spectrometry (DL-CFS) was employed to investigated the absorption transition of excited argon atom at 842.46 nm. Ar (I) 842.46 nm line was adopted due to the tunable wavelength range of available diode laser in this experiment. Excited argon atoms were produced in a glow discharge plasma. CFS signal intensity at 842.46 nm attained maximum at discharge current of 20 mA in 3 Torr (399 Pa) of argon and at magnetic field of 160 mT. Calibration curve of argon was prepared to mix a small amount of argon into 6 Torr (798 Pa) of helium. The signal intensity depended on the 4.4th power of the number density of argon. The 4.4th power dependence is too large to be explained by the theoretically predicted quadratic dependence. When a small amount of molecular nitrogen was mixed into argon plasma, strong suppression of CFS intensity was observed. Molecular gases such as air were found to be unsuitable for the plasma gas to excite the target atoms.