Currently there are three technology used in Explosive detector, Ion mobility spectrometry, Raman spectroscopy，Fluorescence quenching!
What is the difference between these three technology?
Ion mobility spectrometry- Ion mobility spectrometry (IMS)-based trace explosives detectors are gas sampling and analysis instruments,firstly, the collected gas sample is ionized, and then enters the drift tube where there is an electric field. The drift time in the drift tube is related to the molecular mass. The manifestation of this “spectrum” is the different masses collected by the instrument Strength, if a certain value is consistent with the composition of a known explosive, then there is reason to strongly suspect that there is an explosive nearby
Raman spectroscopy-Raman effect: originates from molecular vibration (and lattice vibration) and rotation, so the knowledge of molecular vibrational energy level (lattice vibrational energy level) and rotational energy level structure can be obtained from the Raman spectrum.
Raman effect is the result of the interaction of photons and optical branch phonons. Light irradiates the material to cause elastic scattering and inelastic scattering. The scattered light of elastic scattering is the same component as the excitation light wavelength, and the scattered light of inelastic scattering has components longer and shorter than the wavelength of the excitation light, collectively referred to as the Raman effect .
Fluorescence quenching-The fluorescent sensing film used in the fluorescent explosive detector can enter an excited state and emit fluorescence of another wavelength under the irradiation of incident light of a specific wavelength. In this process, when the electron-rich fluorescent sensing material and the electron-deficient nitroaromatic hydrocarbon explosives come into contact with each other, charge transfer occurs, and the fluorescent sensing film itself is quenched by the excited fluorescence. By photoelectric conversion of the fluorescent signal by the photoelectric detection circuit, the change characteristics of the fluorescent signal can be expressed by the changed characteristics of the electrical signal after the conversion, so as to determine the type of substance
How choose the appropriate explosive detector?
- Ion migration spectroscopy is widely used to identify dangerous goods on the market. It has high sensitivity, identification under normal pressure, online detection, rapid and accurate identification, stable performance, easy use, low cost of consumables and convenient maintenance. . The ion mobility spectrum explosives detector can check whether the luggage contains explosives and other dangerous items without opening the bag. The main reason is that under normal circumstances, the explosives clothes and luggage of the suspect are left and cannot be completely sealed.
- Raman spectroscopy technology requires Raman probes to identify unknown substances, preferably dangerous items that can be seen with the naked eye. In case of security checks, portable Raman spectrometers can be an important tool for rapid, non-contact, and damage-free detection on site. It can directly confirm explosives and chemical hazardous substances, and has obvious advantages especially for the detection of liquid samples.
- Explosives detector with fluorescent polymer sensing technology, In the beginning, only the United States had the technology for detecting fluorescent polymerized explosives, but the United States imposed a technical blockade on China. Most of the trace explosives detectors currently used in China are ion mobility spectrometry detectors imported from the United States. However, in recent years, many fluorescent explosive detectors have appeared in my country, and the technology is relatively inferior to the mature stability of the United States.
