脉冲微放电发射光谱用于合金样品元素分析

发布时间：2018-04-21 04:09

  本文选题：脉冲微放电等离子体 + 光谱分析　； 参考：《光谱学与光谱分析》2017年06期

【摘要】：利用大气压脉冲微放电剥蚀源对铝合金进行光谱分析。该针板结构微放电装置具有价格低廉、操作便捷、分析快速等特点。脉冲放电能瞬间注入极大的放电能量,不致使样品融化,进而保证放电的稳定性。在几微秒的时间内,对钨针电极施加近-4 000V的高压,电极间迅速形成放电通道,针尖和样品之间形成高达20A的电流,造成对样品的剥蚀,并对被剥蚀的粒子进行激发。单次放电脉冲注入能量约为8.5mJ,能量以电流的形式传递于放电电极。剥蚀形貌图表明放电微等离子体局域在电极间隙,针尖轴向上的能量传递和电流密度远高于离轴区域。为了深入研究剥蚀机制和物理性质,对等离子体源的电学特性进行了讨论。通过精确的时序拍摄技术观测了等离子体的演化过程,从ICCD相机的快速成像结果可以看到等离子体源寿命与脉冲高压放电源的脉宽相当,发光强度与放电电流变化趋势相吻合。与光谱分析装置相连接,脉冲微放电剥蚀源可有效激发合金样品中的铝、镁、锰、铜等元素原子谱线。对放电过程等离子体光谱特性进行考察,利用玻尔兹曼斜线法和Stark展宽法计算等离子体电子温度和电子数密度,分别得到过程中等离子体电子激发温度约6 700K,等离子体电子数密度约1017 cm-3量级,并验证了放电处于局域热平衡状态。探究其定量分析性能,结果表明该脉冲微放电等离子体直接作为一种光谱分析源可实现对铝合金样品快速定量分析。
[Abstract]:The spectrum analysis of aluminum alloy was carried out by using atmospheric pressure pulse microdischarge denudation source. The device has the advantages of low price, convenient operation and fast analysis. Pulse discharge can inject a great deal of discharge energy in an instant, which does not cause the sample to melt, thus ensuring the stability of the discharge. Within a few microseconds, the tungsten needle electrode was subjected to a high voltage of -4000 V, and a discharge channel was formed rapidly between the electrodes, and a current of up to 20A was formed between the tip of the needle and the sample, resulting in the denudation of the sample and the excitation of the denudated particles. The single discharge pulse injection energy is about 8.5 mJ, and the energy is transferred to the discharge electrode in the form of current. The denudation topography shows that the energy transfer and current density of the discharge microplasma are much higher than those in the off-axis region in the gap between the electrodes and the axial direction of the tip. In order to study the denudation mechanism and physical properties, the electrical properties of the plasma source are discussed. The evolution process of plasma was observed by precise time sequence shooting technique. From the fast imaging results of ICCD camera, it can be seen that the lifetime of plasma source is equal to the pulse width of pulse high voltage discharge power supply, and the intensity of luminescence is consistent with the trend of discharge current. Connected with the spectrometer, the pulsed micro-discharge denudation source can effectively excite the atomic lines of Al, mg, mn and Cu in the alloy samples. The plasma spectral characteristics during discharge were investigated. The plasma electron temperature and electron number density were calculated by Boltzmann slant method and Stark broadening method. The plasma electron excitation temperature is about 6 700 K and the plasma electron number density is about 1017 cm-3. It is verified that the discharge is in a local thermal equilibrium state. The results show that the pulsed micro-discharge plasma can be used as a direct source of spectral analysis for rapid quantitative analysis of aluminum alloy samples.
【作者单位】： 厦门大学化学化工学院谱学分析与仪器教育部重点实验室;
【基金】：国家重大科研仪器研制项目(21427813) 国家基础科学人才培养基金项目(J1310024)资助
【分类号】：TG115.33
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本文编号：1780857