23 August 2013 The application of reduced absorption cross section on the identification of the compounds with similar function-groups
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Proceedings Volume 8909, International Symposium on Photoelectronic Detection and Imaging 2013: Terahertz Technologies and Applications; 89090X (2013) https://doi.org/10.1117/12.2034343
Event: ISPDI 2013 - Fifth International Symposium on Photoelectronic Detection and Imaging, 2013, Beijing, China
Abstract
Terahertz spectroscopy is a powerful tool for materials investigation. The low frequency vibrations were usually investigated by means of absorption coefficient regardless of the refractive index. It leads to the disregard of some inherent low-frequency vibrational information of the chemical compounds. Moreover, due to the scattering inside the sample, there are some distortions of the absorption features, so that the absorption dependent material identification is not valid enough. Here, a statistical parameter named reduced absorption cross section (RACS) is introduced. This can not only help us investigate the molecular dynamics but also distinguish one chemical compound with another which has similar function-groups. Experiments are carried out on L-Tyrosine and L-Phenylalanine and the different mass ratios of their mixtures as an example of the application of RACS. The results come out that the RACS spectrum of L-Tyrosine and L-Phenylalanine reserve the spectral fingerprint information of absorption spectrum. The log plot of RACSs of the two amino acids show power-law behavior σR(~ν) ∝ (ν), and there is a linear relation between the wavenumber and the RACS in the double logarithmic plot. The exponents α, at the same time, are the slopes of the RACS curves in the double logarithmic plot. The big differences of the exponents α between the two amino acids and their mixtures can be seen visually from the slopes of the RACS curves. So we can use RACS analytical method to distinguish some complex compounds with similar function-groups and mixtures from another which has similar absorption peaks in THz region.
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Fei Yu, Jian Zuo, Kai-jun Mu, Zhen-wei Zhang, Liang-liang Zhang, Lei-wei Zhang, Cun-lin Zhang, "The application of reduced absorption cross section on the identification of the compounds with similar function-groups", Proc. SPIE 8909, International Symposium on Photoelectronic Detection and Imaging 2013: Terahertz Technologies and Applications, 89090X (23 August 2013); doi: 10.1117/12.2034343; https://doi.org/10.1117/12.2034343
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