Study Of Amino Acid By THz Time-Domain Spectroscopy

A general review of THz time-domain spectroscopy of biological molecules is provided in this paper, including sample preparation, optical path design, data processing and spectrum analysis; a program for THz data processing is empoldered by the Matlab language. Considering the phase jump of the data, this program can not only calculate the correct result, but also fasten the speed of data process. The optical characteristics of 11 kinds of amino acids are detected by THz time domain spectroscopy under the condition filled with Nitrogen at room temperature. The absorption and dispersion spectrums are obtained based on the physical model represented by T.D.Doraey and L.D.Duvillaret to abstract the optical parameters of materials in THz range and then the fingerprint of each sample is built in THz range. Comparing the spectrums of absorption and refractive index of the same sample, the relationship between absorption and dispersion is discussed and the Kundt Rule is validated in THz range. The theoretical absorption spectrums of some experimental amino acids are also simulated by Gaussian03 software package. Comparing the different results calculated by different theory models in Gaussian03 with experimental results, the suitable theory for THz spectrum analysis is selected. With the simulated result, the corresponding vibrational models of every absorption peaksare discussed and identified. The results not only fill up the spectra gap of amino acids in far-infrared range, supply data for amino acid molecular identification and conformation analysis, but also provide reference for studying other complex biological molecules by THz time-domain spectroscopy.