四重極型レーザイオン化質量分析装置の分析感度の改善II

概要

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This paper describes the preliminary experiments on improvement of the analytical sensitivity of a quadrupole-based laser ionization mass spectrometer. The effect of the incident angle of the laser beam to the sample surface on the ion intensity was investigated. The experimental result showed that the ion intensity obtained at incident angle of 45° was tenfold higher compared with that obtained at 90°. Next, the ion intensity was measured by varying the laser energy from 3 to 10.5 mJ at various entrance aperture diameters of the ion chamber (1.5, 3, 6, and 12 mmф). The results showed that the ion intensity increased with increasing both the laser energy and the aperture diameter, but too much increased in the laser energy caused a strong background at an aperture diameter of 12 mmф. Finally, in order to bring more ions into the ion chamber, a cylindrical electrode was placed between the ion chamber and the sample and its effect on the ion intensity was investigated. The result indicated that the retarding electric field produced by applying a positive voltage to the electrode was effective to increase the ion intensity.
中部大学の論文
2003-12-15