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High sensitive determination by the use of laser multi-photon ionization.

利用激光多光子电离进行高灵敏度测定。

基本信息

批准号：
60470067
负责人：
OGAWA Teiichiro
金额：
$ 3.65万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1987
项目状态：
已结题

项目摘要

1. Analysis of the laser photoionization current.The current signal of th aromatic molecules in solution consists of a fast signal of electrons and a slow signal of ionz. The current signal is large for those molecule with large molar absorptivities. Its laser wavelength dependence (two-photon ionization spectrum) shows structure similar to the absorption spectrum, but it increases in the shorter wavelength region due to the increase in the ionization efficiency for a larger excess energy.2. High sensitive analysis in solutionThe best wavength for a high sensitive determination has been decided by the use of the two-photon ionization spectrum of each molecule. The high seisitve detection of several aromatic hydrocarbons have been carried out in hexane. The detection limits and detection wavelengths are 20 ppt and 337 nm for pyrene, 50 ppt and 383 nm for perylene, and 20 ppt and 407 nm for naphthacene. The detection limits are considerably lower in polar solvents because of their large dark current.3. High sensitive analysis in gas phaseThe aromatic hydrocarbons in ambient nitrogen gas were detected with excitation by the second harmonics of the dye lasers. The detection limits are 9 ppb for benzene, 8 ppb for toluene, and 0.8 ppb for aniline. The solid aromatic hydrocarbons were determined by thermal evaporation techniques.4. Other applicationsThe laser can be focused in a small spot and is convenient for an application to a detector of a high-performance liquid chromatography system. Also, a small amount of aromatic hydrocarbons on metal surface can be determined by the laser photoionization technique. Preliminary experiments on these subjects have been carried out.

1.激光光致电离电流分析：TH芳香族分子在溶液中的电流信号由电子的快信号和离子的慢信号组成。对于摩尔吸光系数较大的分子，电流信号较大。它的激光波长依赖关系(双光子电离光谱)呈现出与吸收光谱相似的结构，但在较短的波长范围内，由于超额能量较大时电离效率的增加而增加。溶液中的高灵敏度分析高灵敏度测定的最佳波长由每个分子的双光子电离光谱决定。在正己烷中进行了几种芳香烃的高震检测。该方法的检出限和检测波长分别为20 ppt和337 nm，50 ppt和383 nm，环烷20 ppt和407 nm。在极性溶剂中，由于其较大的暗电流，检测下限较低。气相高灵敏分析用染料激光的二次谐波激发检测环境氮气中的芳香烃。苯的检出限为9 ppb，甲苯为8 ppb，苯胺为0.8 ppb。采用热蒸发技术对固体芳烃进行了测定。其他应用激光可以聚焦在一个小光点上，便于应用于高效液相色谱系统的检测器。此外，激光光电离技术还可以测定金属表面的少量芳香烃。已经对这些课题进行了初步的实验。