Raman study of L-Asparagine and L-Glutamine molecules adsorbed on aluminum films in a wide frequency range

Abstract

Using micro-Raman spectroscopy, a detailed study of vibrational spectra of L-Asparagine and L-Glutamine amino acids adsorbed on aluminum foils were carried out within the frequency range 80…3500 cm–1 under different excitation wavelengths. On the basis of detailed analysis of Raman spectra of the mentioned above amino acids and data of DFT-calculations of normal modes and isotopic substitution for these analytes available in literature, interpretation of amino acids vibrational bands were performed. The polarized Raman spectra of studied amino acids indicate different ordering of polycrystalline structure in distinct spots on the sample. The most significant variations of ratios between polarized bands are principally observed for deformation vibrations of NH2, COO– and CH2 groups within entire “fingerprint” range and valence vibrations of CC and CN bonds within the range 1000…1100 cm–1.

Keywords

• amino acid
• L-Asparagine
• L-Glutamine
• vibrational spectroscopy