Application Of Bilateral Clamping Principle In Infrared Spectroscopy

Infrared spectroscopy is one of the effective means to characterize and analyze the structure of the substance. The process of the sample preparation is simple, with the appearance of various infrared accessories, it can meet the requirement of different kinds of sample measurement, thus it is used widely in chemistry and other related subjects. No matter what kinds of preparation and testing methods are selected, the sample is required to be uniform during the process of measurement. The distortion phenomenon signifies the measured spectra cannot represent the actual structure and quantity information of the discontinuous sample. Based on the Bilateral clipping principle, the hybrid single-beam spectrum(2) is defined as a linear combination of the different spectra(1 3) with the different concentrations(thicknesses) of the same sample. It can be expressed as 101312. Under the premise of spectral distortion degree can be neglected, by changing the coefficient of hybrid factor(component factor), the actual adjustable hybrid background single-beam spectrum can be gained. To use this theory as the starting point, we select two appropriate reference samples to control the intensity of the background single-beam spectrum. This new method has eliminated the interference of water peak in aqueous solution successfully. In this paper, we try to solve the distortion problem of the discontinuous sample theoretically, we deeply understand the influencing factors leading to the spectral distortion phenomenon of the sample to be measured. The spectral distortion degree of the discontinuous sample can be quantitatively calculated, the theoretical results and the experimental phenomenon match well. By selecting the proper testing condition, the spectral distortion degree of the discontinuous sample can be minimized. Thus it can provide theoretical and technical guidance to the discontinuous sample in the actual measurement. It is always difficult to eliminate the interference of the complex chemical system which cannot accord with Lambert-Beer s law due to intermolecular interaction. Spectral subtraction technique is being challenged under this circumstance. But still there is of great correlation between concentration of the solution and its corresponding spectrum. According to bilateral clamping principle, the hybrid absorbance spectrum is defined as312 AAA, assuming two different concentrations of the same solution are1 c and3c, their corresponding spectra 1A and3 A are known, thus concentration of the solution between1 c and3c can be expressed in hybrid spectrum2 A.The experimental results show that a real spectrum with a certain concentration can be synthesized by selecting appropriate bilateral absorbance spectra. It makes a further promotion to spectral subtraction technique and is expected to provide a new method for the separation of multi-component spectra. As long as suitable experimental conditions and sample parameters are selected, to use the hybrid spectrum instead of the real spectrum during the procedure of background acquisition is feasible. Finally the quality infrared spectrum without the interference of solvent or other background components can be obtained. This new method can synthesize a intensity controllable hybrid spectrum by using bilateral clamping principle, it provide new ideas for the measurement of multi-component system.