Mass spectrum vacuum ultraviolet ionization source based on optical-window-free gas discharge lamp

Abstract

The invention relates to mass spectrometry instruments, in particular to a mass spectrum vacuum ultraviolet ionization source based on an optical-window-free gas discharge lamp. The mass spectrum vacuum ultraviolet ionization source based on the optical-window-free gas discharge lamp comprises the optical-window-free gas discharge lamp and an ionization source cavity, wherein the optical-window-free gas discharge lamp is fixed to the outer wall of the ionization source cavity, a discharge lamp light outlet of the optical-window-free gas discharge lamp is communicated with the ionization source cavity, vacuum ultraviolet emitted by the optical-window-free gas discharge lamp is located inside the ionization source cavity, ion repulsion electrodes, ion transport electrodes and ion extraction electrodes are arranged inside the ionization source cavity and are arranged in sequence in the emergent direction of the vacuum ultraviolet, and the ion repulsion electrodes, the ion transport electrodes and the ion extraction electrodes are arranged at intervals in a coaxial and parallel mode. According to the mass spectrum vacuum ultraviolet ionization source based on the optical-window-free gas discharge lamp, due to the fact that the vacuum ultraviolet with different energy grades and excited-state atoms / ions with different energy grades are generated through gas discharge, ionization selection and ionization efficiency of sample molecules are improved, influence of pollution of an optical window on signal strength can be eliminated, and detection sensitivity and measurement accuracy of the mass spectrum are improved.

Description

technical field [0001] The invention relates to a mass spectrometer analysis instrument, in particular to a mass spectrometer vacuum ultraviolet photoionization source based on a lightless window type gas discharge lamp. Background technique [0002] Electron impact ionization (EI) is the most widely used ionization source in organic mass spectrometry because of its simple structure, high ionization efficiency, and abundant spectral library resources. However, electrons with an energy of 70eV bombard organic sample molecules, which will produce a large number of fragment ions. When analyzing complex mixtures, the peaks overlap seriously, making it difficult to read the spectrum. It needs to be combined with other analytical methods such as gas chromatography to obtain reliable results. Analytical data are therefore not suitable for real-time, on-line analysis. Vacuum ultraviolet photoionization is a very effective soft ionization method, which directly ionizes material mole...

AI Technical Summary

Problems solved by technology

However, using these special lens materials such as LiF, MgF 2 etc., there will be some problems in practical application

On the one hand, the existing lens materials will limit the photon energy that can be emitted by the vacuum ultraviolet light source. The LiF light window with the highest transmitted photon energy can transmit a photon energy of up to 11.8eV. Organic and inorganic molecules such as CH 4 (IE=12.61eV), acetonitrile (IE=12.20eV), SO 2 (IE=12.35eV) and so on are powerless

On the other hand, the surface of the light window will be polluted due to physical or chemical adsorption during use, and as the pollution intensifies, the outgoing light intensity will gradually attenuate, thus affecting the detection sensitivity and quantitative accuracy of the mass spectrometer. sex

Therefore, vacuum ultraviolet photoionization mass spectrometry is limited in practical applications.

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