Space charge evaluation in a plasma-source mass spectrograph.
Space charge evaluation in a plasma-source mass spectrograph.
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DOI：
10.1021/ac960673t
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发表时间：
1997-02
影响因子：
7.4
通讯作者：
T. Burgoyne;G. Hieftje;R. Hites
中科院分区：
文献类型：
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作者：
T. Burgoyne;G. Hieftje;R. Hites
空间电荷效应及其引起的矩阵干扰是电感耦合等离子体质谱（ICPMS）中存在的问题。以前已经观察到，这些有害的空间电荷效应在扇形场仪器中并不显着存在，这一事实被归因于它们通常使用的高加速势，但没有得到证明。为了检验空间电荷在我们的等离子体源质谱仪（仅在中等加速电位下工作）和其他扇形仪器中的重要性，在撇脂器后面约7厘米处放置了一个石墨盘。电感耦合等离子体运行17h，加入0.01 mM多元素溶液。然后用空间分辨激光烧蚀ICP飞行时间ms对该圆盘进行了分析。第二真空级加速似乎是控制离子束内元素分布的重要因素。在加速电位为800 V时，m/z 208处的离子束宽度是m/z 7处宽度的三分之一；在4000 V的加速电位下，离子束宽度不随质量的变化而变化。
Space charge effects, and the matrix interferences they cause, are problems in inductively coupled plasma mass spectrometry (ICPMS). It has previously been observed that these deleterious space charge effects are not significantly present in sector-field instruments, a fact that has been attributed, but not demonstrated, to the high accelerating potentials they commonly employ. To examine the significance of space charge in our plasma-source mass spectrograph (which operates at only moderate accelerating potentials) and in other sector instruments, a graphite disk was placed approximately 7 cm behind the skimmer. An inductively coupled plasma was operated for 17 h while a 0.01 mM multielement solution was introduced. This disk was then analyzed by spatially resolved laser ablation ICP time-of-flight MS. Second vacuum-stage acceleration appears to be an important factor that governs the elemental distribution within the ion beam. The ion beam width at m/z 208 is one-third of its width at m/z 7 using an accelerating potential of 800 V; at an accelerating potential of 4000 V, the ion beam width does not vary with mass.