A multi-ion gate migration tube and multi-ion gate compression control method

Abstract

The invention discloses a multi-ion gate migration tube and a multi-ion gate compression control method. The multi-ion gate migration tube is sequentially composed of an ionization source, an ionization area, an ion gate area, a migration area and an ion receiving plate from left to right; the ion gate The area is composed of three ion gates, pointing from the ionization source to the direction of the ion receiving plate, which are ion gates a, b, and c in turn. The three ion gates are respectively installed on three consecutive electrode positions on the transfer tube; the ion gates have a uniform , compressed and closed. The ion density per unit volume of the ion cluster in the compressed state becomes larger, and the half-peak width of the formed ion mobility spectrum becomes smaller, which improves the resolution of the ion mobility spectrometer. At the same time, the ion gate in the closed state There is no influence of the emptying area of ​​the traditional BNG gate near c, which improves the sensitivity of the ion mobility spectrometry instrument.

Description

technical field [0001] The invention belongs to the technical field of ion gate control of an ion transfer tube, and particularly relates to a multi-ion gate migration tube and a compression control method of the multi-ion gate. Background technique [0002] Ion mobility spectrometry is a trace chemical analysis technique, which can qualitatively judge the ion species by detecting the migration time of different charged ions. -9 kg), or even picograms (1pg = 10 -12 kg) substances, widely used in the detection of chemical substances and toxic and harmful gases. [0003] An important part of the ion mobility spectrometry instrument is the ion transfer tube. The schematic diagram of the ion transfer tube is shown in the figure below. image 3 shown. The ion transfer tube is connected to the external electric field through the electrodes to generate an axial electric field inside the ion transfer tube. The electric field strength is generally selected between 150 and 1000V / cm ...

AI Technical Summary

Problems solved by technology

[0007] The greater the voltage difference between adjacent electrodes on the ion gate, the stronger the vertical electric field formed, and the stronger the closing ability of the ion gate. However, in 2012, Professor Li Haiyang of the Dalian Institute of Chemical Physics discovered that the traditional mode For a working ion gate, the voltage of one of the electrodes is generally fixed at the voltage value at the electrode position of the transfer tube where the ion gate is located. By adjusting the voltage of the other electrode of the ion gate, the switching between the opening and closing of the ion gate is realized. At the same time, the voltage of the other electrode will also act on the electrode near the ion gate, thereby affecting the electric field strength near the ion gate, and an obvious ion emptying area will be generated on both sides of the ion gate, and its axial depth is much larger than that of the BNG gate. The diameter of the electrode is equivalent to the distance between the electrodes, so that when the ion gate changes from the closed state to the open state, the ion clusters in the ionization area need to pass through the clearing area before passing through the ion gate, and finally enter the migration area, so that they can enter the migration area within the opening time At the same time, when the ion gate changes from the open state to the closed state, the clearing area in the migration area will also consume some of the ion volume that has entered the migration area, so that the ion volume that finally reaches the ion receiving plate is further reduced. Decreased signal intensity and reduced sensitivity in ion mobility spectrometry

Therefore, there is an optimal value for the working voltage of the ion gate. If the voltage difference is too small when the gate is closed, the closing ability of the ion gate will be weakened, and the baseline of the ion mobility spectrum signal is high. If the voltage difference is too large when the gate is closed, the sensitivity of the ion mobility spectrum will be weakened.

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