Time-of-flight mass spectrometer for measuring ratio of nano-particle component elements in real time

Abstract

The invention relates to a time-of-flight mass spectrograph, in particular to a time-of-flight mass spectrometer for measuring ratio of nano-particle component elements in real time, comprising a pulse sampling device, a beam source chamber and a time-of-flight mass spectrum mass analyzer provided with an ionization chamber. The time-of-flight mass spectrometer is characterized in that the ionization chamber is positioned in the time-of-flight mass spectrum mass analyzer, the front end of the pulse sampling device is connected with a pulse valve, the pulse sampling device is inserted into the beam source chamber, the beam source chamber is positioned directly above the laser ionization chamber, the outlet of the beam source chamber is connected with the laser ionization chamber through a nozzle, a nanosecond long wavelength high-energy laser is installed at the outer side of the time-of-flight mass spectrum mass analyzer, the high-energy laser beams emitted by the laser pass through the ionization chamber vertically so as to ionize nano-particles completely into univalent and high valence ions, the ratio of the high valence ions can accurately reflect the ratio of nano-particle component elements, and the ions produced by ionization can be recorded by the time-of-flight mass spectrograph. The invention can measure the ratio of nano-particle component elements rapidly, and the measurement is not influenced by ionization laser energy.

Description

technical field [0001] The invention belongs to a mass spectrometer, and in particular relates to a time-of-flight mass spectrometer which uses a laser ionization method to measure the composition element ratio of nanoparticles. Through this technology, the composition element ratio of nanoparticles with a particle size less than 10nm can be measured in real time. . Background technique [0002] Aerosol is a dispersed phase system formed by solid or liquid particles dispersed in a gaseous medium, and is an important part of the earth's atmosphere. Aerosols can be divided into primary aerosols and secondary aerosols according to their sources. Primary aerosols come from the direct fragmentation process of solid and liquid substances, such as dust, sea wave splash, ocean bubble burst and volcanic eruption. The main source of secondary aerosols is gas-particle transformation, and some important pollution processes such as acid rain and photochemical smog are related to this. ...

AI Technical Summary

Problems solved by technology

Gas-particle transformation to form new particles is a very complex physical and chemical process. Scholars represented by Kulmala proposed a new view of nucleation and growth process (Atomos.Chem.Phys., 2004, 4: 2553; J.Aerosol Sci.2004, 35:143-176), it is believed that there may be a large number of thermodynamically stable subnanoparticles in the atmosphere, and these subnanoparticles are the source of the nucleation process, but because the particle size of these particles is too small, there is no suitable instrument to detect them Therefore, how to measure nanometer-sized (0.5-5nm) particles in the atmosphere and know their chemical composition and structure is the key to understanding the mechanism and evolution of new atmospheric particles

[0003] Due to the low collection efficiency, high reactivity and poor stability of nanoparticles, the chemical composition of nanoparticles may change or be contaminated when measured using traditional off-line techniques

The online aerosol mass spectrometry technology developed in recent years, such as laser ionization single particle aerosol mass spectrometry (Aerosol Time-of-flight Mass Spectrometry, ATOFMS) represented by Prather and electron bombardment ionization aerosol mass spectrometry (Aerosol Mass Spectrometer) by Aerodyne Company , AMS), have achieved success in aerosol source apportionment and heterogeneous chemical reaction research, but these two aerosol mass spectrometry techniques use continuous aerodynamic lens injection, and the transmission efficiency of aerosol particles with a particle size of less than 50nm Low. And AMS needs to desorb the aerosol particles first and ionize them by electron bombardment, so it cannot measure the refractory inorganic components in the aerosol particles

The laser can effectively ionize almost all elements, but the laser power used in ATOFMS is low. The outer elements in the aerosol particles are easier to ionize than the inner elements, and there is a phenomenon of incomplete ionization. Only qualitative information of particle composition can be obtained, but quantitative information cannot be obtained.

Images