Infrared spectroscopy is mainly used to study compounds with even polar rectangular variations in vibrations (the vibrations without even polar rectangular variations occur in the laman spectra). Thus, with the exception of single atoms and co-nuclear molecules such as ne, he, h2, almost all organic compounds are absorbed in the infrared spectral zone. With the exception of the optical isomers, certain high-molecular mass polypolymers and compounds with small differences in molecular weights, there must be no identical infrared spectrum for two compounds with different structures. The wavelength position of the infrared absorption band is usually related to the strength of the absorption band, reflecting the characteristics of the molecular structure, which can be used to identify the structural composition of the unknown or its chemical base group, while the absorption strength of the absorption band is related to the molecular composition or the concentration of the chemical matrix, which can be used for quantitative analysis and purity determination. Because of the strong characteristics of the infrared spectrum analysis, samples of gases, liquids and solids can be measured and have low usage, speed of analysis and do not damage the characteristics of the samples. Thus, the infrared spectroscopy method is not only as capable of qualitative and quantitative analysis as many other analytical methods, but is also one of the most useful methods for identifying compounds and determining molecular structures. Infrared spectroscopy detection methods include, inter alia, furier infrared spectrum (ftir) and non-dispersible infrared spectrum (ndir) technology using broadband light sources, and infrared laser spectroscopy technology. Compared to ftir and ndir using broadband light sources, infrared laser spectral spectra, with high unicolor infrared lasers as a light source with higher spectral resolution, does not require the use of additional spectroscopy components and can easily be miniaturized. In addition, high-power density laser light sources facilitate long-range detection。
