Raman spectroscopy and inelastic neutron scattering study of crystalline L-valine

• Published in: Journal of physics. Condensed matter Vol. 21; no. 41; pp. 415404 - 415404 (7)
• Main Authors: da Silva, J H, Lima Jr, J A, Freire, P T C, Lemos, V, Mendes Filho, J, Melo, F E A, Pizani, P S, Fischer, J, Klemke, B, Kemner, E, Bordallo, H N
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 14.10.2009; Institute of Physics
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Organic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Specific heat; Raman spectra; Inelastic scattering; Hydrogen bonds; Valine; Amino acids; Molecular reorientation; Neutron diffusion; Crystal structure
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/21/41/415404

Information about the strength of the hydrogen bond interactions in crystalline L-valine was obtained by Raman and inelastic neutron scattering spectroscopies. Raman studies were carried out from room temperature up to 423 K in order to examine both the external and the internal vibrations in L-valine. The structure seems to be stable above room temperature since no indication of a phase transition or clear indication of reorientation of L-valine molecules was observed. From the inelastic neutron scattering measurements, made between 270 and 320 K, for fully hydrogenated and partially deuterated L-valine, a better description of the low frequency modes was possible. Moreover it was possible to establish that the phase transition at low temperatures is related to the activation of an infrared mode in the Raman spectra. Additionally the low temperature phase of L-valine was further characterized by means of specific heat measurements between 5 and 350 K.