Study On Infrared Spectra Of The Non-Lambert-Beer-Law System

Infrared spectroscopy is one of the effective techniques to characterize and analyze the structure of the substance. With the advantages of the simple sampling techniques, the convenient operation, high sensitivity and other benefits, the technology of infrared spectroscopy has become an indispensable tool for the analysis and measurement in various fields. The infrared spectrum can analyze various kinds of samples, and the basic requirement of the sample is uniform. The spectra of the non-uniform samples cannot reflect the actual information of the sample, which can lead to the distortion of the IR spectrum. This paper puts forward the concept of hybrid single-beam spectrum to study the distortion of the IR spectrum caused by non-uniform sample. A hybrid single-beam spectrum can be expressed as=0; = 1+(1- )2(0 ≤ ≤ 1). We have been quantitatively explored the properties and the distortion of the hybrid single-beam spectrum by the mathematical relation and error theory. It can be obtained the conditions regardless of the distortion degree by calculating. Thus, the hybrid single-beam spectrum can become the ideal background single-beam spectrum for the distorted degree is exceedingly low and the strength can be adjusted. The proposed methodology expands range of the deduction of background absorption peak and provides theoretical and technical guidance for the measurement of real samples.Water is an extremely versatile solvent. However, there are serious problems for strong absorption peak of water in the measurements of infrared spectroscopy. Especially, the structure of water molecular has changed for dissolved some salts, and the spectral subtraction of the FTIR cannot play a role. We propose hybrid absorbance spectrum to solve this problem. The formula for the definition of a hybrid absorbance spectrum is = α1+(1-α)2(0 ≤ ≤ 1), supposing two different concentration of the same solution are 1 and 2, their corresponding are known, the concentration of solution between 1 and 2 can be represented by a corresponding hybrid absorbance spectrum. As long as selecting the proper spectra 1 and 2, the degree of distortion of the hybrid absorbance spectrum can be minimized. The basis of the quantitative analysis for the absorption spectroscopy is Lambert-Beer Law. However, the Lambert-Beer Law is only applicable in ideal conditions. And during the actual measurement, there often are many factors not to obey the limited conditions. Our proposed method can overcome this trouble through selecting appropriate spectra 1 and 2 to synthesize hybrid absorbance spectrum. The results of experiments proved that the hybrid spectral method is better than conventional spectral subtraction technology in deducting background interference group to obtain the high quality infrared spectroscopy, and is simple and efficient, which provides a new method for the measurement of system which does not meet the Lambert-Bill law.