Zobrazeno 1 - 10
of 150
pro vyhledávání: '"Melo, F. E. A."'
We present a Raman spectroscopy investigation of the vibrational properties of L-histidine crystals at low temperatures. The temperature dependence of the spectra show discontinuities at 165 K, which we identify with modifications in the bonds associ
Externí odkaz:
http://arxiv.org/abs/1304.7692
Akademický článek
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Autor:
Filho, P. F. Facanha, Freire, P. T. C., Lima, K. C. V., Filho, J. Mendes, Melo, F. E. A., Pizani, P. S.
Single crystal samples of L-leucine, C6H13NO2, a fundamental aliphatic amino acid of the human body, have been studied by Raman spectroscopy at temperatures from 300 to 430 K over the spectral range from 50 to 3100 cm-1. A tentative assignment of all
Externí odkaz:
http://arxiv.org/abs/0704.2792
Autor:
Faria, J. L. B., Paschoal, C. W. A., Freire, P. T. C., Ayala, A. P., Melo, F. E. A., Filho, J. Mendes, Santos, I. A., Eiras, J. A.
The structural changes in Sr(0.66)Ba(0.34)Nb2O6 single crystal fibers when the temperature decreases from 295 to 10 K is investigated by dielectric constant measurements and Raman spectroscopy. The anomaly observed in the plot of e is associated to t
Externí odkaz:
http://arxiv.org/abs/cond-mat/0108341
Autor:
Lima, K. C. V., Souza, A. G., Ayala, A. P., Filho, J. Mendes, Freire, P. T. C., Melo, F. E. A., Araújo, E. B., Eiras, J. A.
Raman spectra of PbZr1-xTixO3 ceramics with titanium concentration varying between 0.40 and 0.60 were measured at 7 K. By observing the concentration-frequency dependence of vibrational modes, we identified the boundaries among rhombohedral, monoclin
Externí odkaz:
http://arxiv.org/abs/cond-mat/0008440
Autor:
Varela, A. T., Sasaki, J. M., Guedes, I., Freire, P. T. C., Ayala, A. P., Filho, J. Mendes, Melo, F. E. A., Chaves, A. S.
X-ray scattering measurements are performed in order to verify % that the mechanism leading to the DC electric field induced $C_{2v}^{19} \to C_{2v}^{\neq 19}$ phase transition in KDP crystal at 119 K is the changing of the local sites symmetries of
Externí odkaz:
http://arxiv.org/abs/cond-mat/0001364
Autor:
Teixeira, A. M. R., Freire, P. T. C., Moreno, A. J. D., Sasaki, J. M., Ayala, A. P., Filho, J. Mendes, Melo, F. E. A.
Pressure-dependent Raman scattering studies in the range 0.0 -- 32 kbar were carried out in L-alanine in order to investigate its external mode phonon spectra in relation to the phase transitions in the crystal. A careful analysis of the spectra show
Externí odkaz:
http://arxiv.org/abs/cond-mat/0001212
Autor:
Filho, A. G. Souza, Freire, P. T. C., Ayala, A. P., Sasaki, J. M., Guedes, I., Filho, J. Mendes, Melo, F. E. A., Araújo, E. B., Eiras, J. A.
This work reports on the systematic high pressure Raman studies in the PbZr$_{1-x}$Ti$_x$O$_3$ ($0.02 \leq x \leq 0.14$) ceramics performed at room temperature. The pressure dependence of the Raman spectra reveals the stable phases of the material un
Externí odkaz:
http://arxiv.org/abs/cond-mat/0001088
Autor:
Filho, A. G. Souza, Freire, P. T. C., Sasaki, J. M., Guedes, I., Filho, J. Mendes, Melo, F. E. A., Araújo, E. B., Eiras, J. A.
We have investigated the behavior of the PbZr(0.94}Ti(0.06)O3 Raman spectra as a function of Hydrostatic pressures. The new structural phases were identified based on previous works performed in PZT system with different Ti concentrations at room- an
Externí odkaz:
http://arxiv.org/abs/cond-mat/9905380
Akademický článek
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