| Terahertz (THz) radiation, which is a kind of electromagnetic wave between the infrared and microwave bands, belongs to far-infrared band. THz time-domain spectroscopy (THz-TDS) which developed in the 1980's has the advantages of high signal to noise ratio, obtaining the absorption coefficient and refractive index of the sample at one time , low energy that can not distroy the biology organise and so on. THz-TDS has been utilized in research fields of material, biology and so on.This thesis investigated absorption spectra of 20 standard polycrystalline α-Amino Acids utilizing the facilities provided by THz spectrum and imaging laboratory of Capital Normal University. The absorption and refractive index spectra have been obtained in effective frequency. Comparing the absorption spectra of compound with similar structure, we conclude the different structures affect the absorption spectra of THz. Eight classes in these 20 amino acids THz absorption spectra are reported for the first time, and others compared with those of published amino acid spectra data. The absorption spectra of structure isomers, enantiomers and racemic compounds of several amino acids have been obtained, and the vibration modes of structure isomers and the different absorption spectra between enantiomers and racemic compounds have been analyzed. Two kinds of amino acids are mixed in different proportion; the intensity of absorption peaks depends on the content of the amino acids. This result indicates that THz time-domain spectroscopy can be used to analyze the molecule content in mixture.This thesis indicates that amino acids have sensitive THz absorption spectra. Every amino acid has different characteristic absorption peaks. Using THz absorption spectra can distinguish different kinds of amino acids, enantiomers and racemic compounds and structure isomers. Compared the THz spectra according to category of amino acids, the relativity between THz absorption spectra and structure of amino acids can be seen.
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