Espectroscopia Raman em Cristais de L-Valina Deuterada e L-Isoleucina sob altas pressões

Abstract

In this thesis, are studied by Raman spectroscopy of two amino acid crystals subjected to conditions of high pressures. The rst is a sample of deuterated L-Valine. Initially, an attempt was made to identify all the bands that appear in the Raman spectrum of deuterated L-Valine, comparing with the results of L-Valine hydrogenated in the literature. The following study was conducted on the sample compressed in a cell with argon pressure to extremes of diamonds in the range between 0:0 GPa and 12 GPa this study can conclude that between 0:0 and 1:3 GPa, the L-Valine su ers a deuterated structural change, according to information provided by the Raman spectra of the material in the region of external modes. At higher pressures, between 5 GPa and 7 GPa, changes occur in the Raman spectra in nearly all spectral regions, which also points to a possible conformational change of molecules in the unit cell. It also provided the values (∂wj/∂P)t for the various modes of vibration of the crystal at various stages presented by the same. The second investigation was the amino acid L-Isoleucine, which was studied by Raman spectroscopy under high pressures up to about 7:5 GPa with the compressor as a liquid mineral oil. Analysis in the spectral region 50 cm⁻¹ { 3200 cm⁻¹, one can infer that above 2:5 GPa and 5:0 GPa large conformational changes occur in the molecule of L-Isoleucine in the unit cell. When you make a graph of the wave number of two-mode network of the crystal of L-Isoleucine investigated as a function of pressure, there are clear discontinuities at approximately 2:3 GPa and 5:0 GPa These changes were associated with changes in the connections hydrogen, since the major changes were observed in the frequency bands associated with the NH₃⁺ rocking and the rocking of CO₂.