Raman scattering in chiral-pure and racemic phases of tryptophan and tyrosine polycrystals

Raman spectra of tryptophan and tyrosine polycrystals have been analyzed in a wide spectral range by fiber-optic spectroscopy. The Raman spectra have been recorded with a BWS465-785H spectrometer in the spectral range of 0–2700 cm$^{-1}$ using a 785-nm cw laser as an excitation source. Parameters of the Raman spectra are compared for three crystalline phase modifications of aromatic amino acids: left-handed, right-handed, and racemic phase. The presence of strong Raman satellites, the characteristics of which change depending on the type of the chiral phase state of amino acid, is found in the low-frequency Raman spectra of tryptophan and tyrosine amino acid lattices. The results obtained can be used for monitoring the chiral purity of bioactive preparations containing amino acids.