Pressure and temperature-dependent gauche-trans isomerization of 1-bromopropane: Raman measurement and statistical thermodynamic analysis

1999 ◽  
Vol 110 (5) ◽  
pp. 2498-2507 ◽  
Author(s):  
Min-Hom A. Hu ◽  
Luis E. S. de Souza ◽  
Meng-Rong Lee ◽  
Dor Ben-Amotz
Keyword(s):  
Thermodynamic Analysis ◽  
Statistical Thermodynamic ◽  
Temperature Dependent ◽  
Trans Isomerization ◽  
Raman Measurement

MULTIFERROIC MATERIALS Bi1-xSmxFeO3: A STUDY OF RAMAN AND ABSORPTION SPECTROSCOPIES

2010 ◽  
Vol 19 (02) ◽  
pp. 247-254 ◽  
Author(s):  
NGUYEN VAN MINH ◽  
DAO VIET THANG
Keyword(s):  
Lattice Dynamics ◽  
Optical Band Gap ◽  
Solid State Reaction Method ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Lattice Constants ◽  
Raman Measurement

Multiferroic Bi 1-x Sm x FeO 3(x = 0.00, 0.05, 0.1, 0.15, 0.2) ceramics were prepared by conventional solid state reaction method. X-ray diffraction measurement was carried out to characterize the crystal structure and to detect the impurities existing in these ceramics. The substitution of rare earth Sm for Bi was found to decrease the impurity phase in BiFeO 3 ceramics. There is strong evidence that both lattice constants a and c of the unit cell become smaller as the Sm 3+ content is increased. The effect of introducing Sm 3+ is shown to decrease the optical band gap for doped sample Bi 1-x Sm x FeO 3. Additionally, the temperature-dependent Raman measurement performed for the lattice dynamics study of Bi 1-x Sm x FeO 3 samples reveals a strong band centered at around 1000–1300 cm-1 which is associated with the resonant enhancement of two-phonon Raman scattering in the multiferroic Bi 1-x Sm x FeO 3 samples. This two-phonon signal is shown to broaden with increasing x. The Raman spectra at low wavenumbers are suggested to be related with magnon in this system.

Thermodynamic Analysis of Reaction Equilibria in Ionic and Molecular Liquid Systems by High-Temperature Raman Spectroscopy

2009 ◽  
Vol 63 (9) ◽  
pp. 1050-1056
Author(s):  
Angelos G. Kalampounias ◽  
Soghomon Boghosian
Keyword(s):  
Raman Spectroscopy ◽  
High Temperature ◽  
Complex Formation ◽  
Equilibrium Constant ◽  
Thermodynamic Analysis ◽  
Raman Band ◽  
Thermal Dissociation ◽  
Temperature Dependent ◽  
Liquid Systems ◽  
Molten Phase

A formalism for correlating relative Raman band intensities with the stoichiometric coefficients, the equilibrium constant, and the thermodynamics of reaction equilibria in solution is derived. The proposed method is used for studying: (1) the thermal dissociation of molten KHSO4 in the temperature range 240–450 °C; (2) the dinuclear complex formation in molten TaCl5–AlCl3 mixtures at temperatures between 125 and 235 °C. The experimental and calculational procedures for exploiting the temperature-dependent Raman band intensities in the molten phase as well as (if applicable) in the vapors thereof are described and used for determining the enthalpy of the equilibria: (1) 2HSO4−( l) ↔ S2O72–( l) + H2O( g), Δ H0 = 64.9 ± 2.9 kJ mol−1; and (2) 1/2Ta2Cl10( l) + 1/2Al2Cl6( l) ↔ TaAlCl8( l), Δ H0 = −12.1 £ 1.5 kJ mol−1.

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