an electron ionization source

Abstract

The invention provides an electron ionization source, including an electron source, a repulsion electrode and an ion lens, and further including a first cylindrical component, an annular component and a second cylindrical component, wherein the electron source is arranged at the side part of the first cylindrical component, the repulsion electrode is arranged in the first cylindrical component with two open ends, the annular component is arranged on one side of the first cylindrical component, one side, far away from the first cylindrical component, of the annular component is provided with an outlet, and the inner diameter of the hollow inner part of the annular component is gradually reduced along the emitting direction of ions, the second cylindrical component is arranged in the outlet, and the iron lens is arranged on one side of the second cylindrical component along the emitting direction of the ions. The electron ionization source has the advantage of being high in ion emitting efficiency.

Description

technical field [0001] This invention relates to mass spectrometry and, in particular, to electron ionization sources. Background technique [0002] Gas chromatography-mass spectrometry instrument is one of the important members in the field of analytical instruments. The mixed organic molecules enter the mass spectrometer after being separated by the gas chromatography column. The mass spectrometer ionizes the organic molecules and makes various ions under the action of electric field or magnetic field. Separation is carried out according to the mass-to-charge ratio, and the corresponding intensity is detected. The obtained mass spectrum signal can be used for qualitative identification and quantitative analysis of substances. [0003] The ion source of the gas chromatography-mass spectrometry instrument is mainly an electron ionization source (EI). The EI source is composed of a semi-closed ion box and a set of lenses. In the ion box, there is a filament at both ends of t...

AI Technical Summary

Problems solved by technology

The electric field simulation of the ion box on the current commercial mass spectrometer is carried out by the ion optics simulation software. It shows that due to the small opening of the ion box, it is difficult for the external lens to affect the electric field inside the ion box, and the electric field inside the ion box is mainly repelled. The ion optics simulation shows that most of the ions hit the wall of the ion box, and only a small part of the ions (only 40%) can enter the lens group of the ion source through the small hole, and the ion transmission efficiency is low.

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