激光后电离技术对高电离能元素的信号增强

Laser Postionization Technique for Enhancing Signals of High Ionization Potential Elements

  • 摘要: 固体样品的元素分析一直是分析化学重点关注的对象。激光作为一种固体直接采样和电离技术,常与飞行时间质谱联用,用于固体样品的元素分析。然而,对于高电离能元素的检测往往需要较大的激光功率密度,导致其离子的动能分散较大,严重影响谱图分辨率。本研究使用激光解吸/激光后电离质谱法(解吸激光波长515 nm,后电离激光波长266 nm)对固体样品中的Pd、Sb、Cd、Au等高电离能元素进行分析。一方面,采用较弱的解吸激光能量解决了强激光解吸电离所带来的动能分散问题,显著提高了谱图分辨率;另一方面,利用较强的后电离激光电离原来被“浪费”掉的绝大部分中性原子,提高原子利用率和仪器灵敏度。该方法无需任何样品前处理、分析时间短、操作简单,适用于固体中高电离能元素的快速检测。

     

    Abstract: Elemental analysis of solid samples has always been the focus point of analytical chemistry. As a direct solid sampling and ionization technique, laser is often used in conjunction with time-of-flight mass spectrometry for the elemental analysis of solid samples. For the detection of high ionization potential elements, a large laser power density is often required, which results in widely dispersed kinetic energy of ions and deteriorated spectral resolution. Laser desorption/laser postionization mass spectrometry with desorption wavelength of 515 nm and postionization wavelength of 266 nm was used to detect high ionization potential elements such as Pd, Sb, Cd, and Au in this paper. On the one hand, the weak desorption laser energy greatly alleviates the problem of large kinetic energy dispersion and significantly improves the spectral resolution. On the other hand, laser postionization utilizes the “wasted” neutral atoms to improve the atomic utilization and the sensitivity of the instrument.With no sample pretreatment, this method requires short analysis time and simple operation.This method is applicable for rapid detection of high ionization potential elements in solid.

     

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