Espectroscopia Raman em Cristais de L-Valina Deuterada e L-Isoleucina sob Altas PressÃes / Raman Spectroscopy in Crystals Deuterated L-valine and L-isoleucine in High Pressures

AUTOR(ES)

Adelmo Santiago Sabino

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

24/09/2010

RESUMO

In this thesis, are studied by Raman spectroscopy of two amino acid crystals subjected to conditions of high pressures. The first 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 litera- ture. 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 suffers 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 con- formational change of molecules in the unit cell. It also provided the values (∂ωj/∂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 1/cm - 3200 1/cm , 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-.

ASSUNTO(S)

fisica da materia condensada espectroscopia raman aminoÃcidos pressÃo raman spectroscopy amino acids pressure

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