Production of Microwave-Induced Helium Plasma at Atmospheric-Pressure and Its Application to Mass Spectrometry for Trace Element Analysis

用Okamoto腔(7(1991)283-289)工作于表面波模式，产生了用于痕量元素分析的高功率(1.5kW，2.45 GHz)大气压氦微波诱导等离子体。通过测量等离子体(环形)的发射强度和质量强度，考察了等离子体的基本分析特征。其中一段为简化的扁平矩形波导(厚度：6.4 mm，宽度：109.2 mm)。另一部分是模式转换，它由内导体和端接在前板上的外圆柱形导体组成。前板与内导体前缘GAP之间的距离为5至10 mm。表面波在缝隙中被激发，得到了氦在200-850 nm范围内的发射光谱的空间分布。氦等离子体发射的He I(587.6 nm，23.0eV)、He I(388.9 nm，23.0eV)和He I(667.8 nm，23.1eV)等。The Domina…更多的NT峰是He I(587.6 nm)弱背景峰，OH(306.4 nm，4.1 eV)和O I(777.6 nm，10.7 eV)。气体样品(100ppm)，Ar气体样品(Ar，电离势：15.8 eV)或氮气(N2，15.5 eV)，可检测到Ar I(811.5 nm)或Ni(746.8 nm)发射。等离子体是一种敏感的电离源。溶液样品(Fe：1000ppm)通过内管使用超声雾化器引入等离子体，而不使用解溶系统(实验室建立)。用Ar-ICP气动雾化器使等离子体变得不稳定，用玻尔兹曼发射强度图和跃迁过程中上能态的能量得到了Fe_i激发温度。在微波功率为1kW时，获得了5500K的激发温度，计算出电子密度为10^&lt；14&gt；/cm~3。这些值表明等离子体是最有用的激发和/或电离源。这项工作的更多细节及其在质谱学中的应用目前正在我们实验室进行研究，并将在近期发表。较少

A high power (1.5 kW,2.45 GHz) atmospheric pressure helium microwave-induced plasma for trace elemnt analysis was produced using a Okamoto cavity (J.Anal.At.Spectrom., 7 (1991) 283-289) operated in a surface wave mode. The fundamental analytical features of the plasma (annular-shaped) ware examined by measuring the emission and mass intensities.The cavity, nonresonant and with no cooling, consists of two parts. One section is a reduced flat rectangular waveguide (thickness : 6.4 mm, width : 109.2 mm). The other section is a mode transfer which consists of an inner conductor and an outer cylindrical conductor terminated by a front plate. The distance between the front plate and the front edge of the inner conductor, gap, is 5 to 10 mm. The surface wave is excited in the gap.Spatial profiles of the emission spectra for helium obtained from 200 to 850 nm. Emissions from the helium plasma were He I (587.6 nm, 23.0 eV), He I (388.9 nm, 23.0 eV) and He I (667.8 nm, 23.1 eV) et al. The domina … More nt peak was He I (587.6 nm) Weak background peaks obtained for OH (306.4 nm, 4.1 eV) and O I (777.6 nm, 10.7 eV).Gas sample (100 ppm) ; argon (Ar, ionization potential : 15.8 eV) or nitrogen (N_2,15.5 eV) introduced into the helium plasma and Ar I (811.5 nm) or N I (746.8nm) emission could be detected. The plasma is a sesitive ionization source.Solution sample (Fe : 1000 ppm) was introduced into the plasma through the inner tube using an ultra sonic nebulizer without a desolvation system (laboratory built). Using a pneumatic nebulizer of an Ar ICP,the plasma became unstable.The Fe I excitation temperatue was obtained from the Boltzmann plot of emission intensities vesus the energy of the upper state in the transition. The excitation temperature of 5500 K was obtained and electron density of 10^<14>/cm^3 was calculated at the microwave power of 1kW.These values show that the plasma is the most useful excitation and/or ionization source for trace element analysis.More details of this work and its application for mass spectrometry are currently being investigated in our laboratory and willbe published in the near feature. Less