【摘要】 为提高电感耦合等离子体质谱仪(ICP-MS)的检测灵敏度,理解电感耦合等离子体(ICP)激发源中取样锥对分析元素电离机理的影响至关重要。借助于激光诱导荧光技术,研究了ICP-MS和电感耦合等离子体原子发射光谱仪(ICP-AES)中,钡原子、基态及亚稳态离子在等离子体内的空间分布差异,重点说明取样锥对分析元素原子化及离子化机理的影响。在ICP-MS中,相较于ICP-AES,水冷取样锥的插入对分析元素轴向分布有复杂影响;取样锥锥前0~2mm内,钡原子及离子荧光信号显著降低,可归因于取样锥对等离子体温度的影响及第一真空室真空压力对分析元素的加速作用;而取样锥锥前2~10mm范围内,由于取样锥的存在,一价钡离子的数密度显著升高。因此推断在高温等离子体内,存在大量的二价钡离子;而在ICP-MS中,一价钡离子荧光信号的增强为中性原子、一价及二价离子之间相互转化的结果。更多还原

【Abstract】 In order to enhance the detection sensitivity of inductively coupled plasma source mass spectrometer(ICP-MS),it is very important to understanding the influence of sampling cone in ICP excitation source on the ionization mechanism of analytical elements.The space distribution difference of barium atom,ground state and metastable ion in plasma of ICP-MS and inductively coupled plasma atomic emission spectrometer(ICP-AES)was investigated by means of laser induced fluorescence technology.The influence of sampling cone on atomization and ionization mechanism of analytical elements was discussed.The insertion of water-cooling sampling cone had more complex influence on the axial distribution of analytical elements in ICP-MS compared to that in ICP-AES.The fluorescence signals of barium atoms and ions decreased significantly within 0-2 mm before sampling cone,which was due to the influence of sampling cone on temperature of plasma as well as the acceleration effect of vacuum pressure in the first vacuum chamber on analytical elements.In range of 2-10 mm before sampling cone,the number density of monovalent barium ions increased significantly cue to the presence of sampling cone.Therefore,it could be concluded that there were a lot of divalent barium ions in high temperature plasma.In ICP-MS,the enhanced fluorescence signal of monovalent barium ions was due to the mutual transformation among neutral atoms,monovalent and divalent ions.更多还原