关于ICP激发机理的讨论述评

COMMENT ON THE DISCUSSION OF THE EXCITATION MECHANISM IN THE INDUCTIVELY COUPLED ARGON PLASMA

根据光谱学家们的讨论,本文认为约在1976年以前有两种不同观点:一种为 ICP中存在 LTE,而另一种则持否定意见,约1977年后,大多数光谱学家基本认为后一种意见是正确的,本文所列举的部分 ICP 激发机理模型,部分地解释了为什么在同一等离子体内会出现不同类型温度以及电子数密度的"过密"现象.通过对 Boum(?)ns和 Lovett 的机理模型比较认为,实验过程选用一定的操作参数和计算过程采用一定的常数对机理的提出极为重要。至今所提出的激发机理还不能令人十分满意。

Inductively coupled plasma(ICP)as an atomization,ionization and exci- tation source has gained great popularity for spectrochemicai analysis,Many authors have studied excitation mechanisms in argon ICPs.Two different conclusions had been made before 1976,one of which believed that local the- rmal equilibrium (LTE) existed in ICP while the other did negatively.After 1977,it is generally accepted that the ICP operated in argon is not in LTE,at least not in the region used for analytical observation between 5 and 30 mm above the rf-coil. The discussion on the excitation mechanism has then concentrated on the explanation of some phenomena as follows,the number density of electrons and excited atoms/ions remarkably deviates from those calculated from Boltzmann's law;various temperatures in ICP differ from each other,It is also evident that there are higher sensitivities of ionic lines,or overpopula- tion of ions. The mechanisms cited in this paper may explain some different pheno- mena from their own experiment.But none of them is satisfied to be used and a more effective one is therefore expected which will need quantitative data more completely and correctly on the spatial distribution of electrons, argon ions and argon metastables.