[Infrared, Raman and density functional study of vibration spectra of 2, 3-dichloropyrazine].

Fourier transform infrared (FTIR) spectra of 2,3-dichloropyrazine in the region 400-4000 cm(-1) were measured under solid state condition using KBr pellets method and liquid state by the melting method, besides, a Fourier transform Raman (FT-Raman) spectra in region 600-4 000 cm(-1) was recorded. Then equilibrium geometry of 2,3-DCP was optimized, and based on this, the harmonic vibrational frequencies, infrared intensities and Raman activities were calculated using B3LYP method of the density function theory (DFT) in conjunction with 6-311++G(2df, 2pd) basis set, furthermore, a comprehensive anharmonic calculation was also been performed for obtaining more accurate vibrational frequencies using second-order perturbation theory treatment based on quadratic, cubic and quartic force constants. Infrared and Raman spectra were simulated corresponding to theory.

Dielectric constant of polyhydric alcohol-DMSO mixture solution at the microwave frequency.

Dielectric spectrum of polyhydric alcohol (1,2,3)-DMSO (dimethyl sulfoxide) mixtures, at full concentration, have been determined by the dielectric relaxation spectroscopy (DRS) method at frequencies from 20 MHz to 20 GHz at room temperature. The mixture behavior is described according to four Davidson-Cole terms whose evolution with composition is analyzed. The binding energies and hydrogen bond (HB) numbers between solute-solute and solvent-solute pairs are obtained from the permittivity using the Luzar model.

Composition-dependent dielectric properties of DMF-water mixtures by molecular dynamics simulations.

In this paper, we study the dielectric properties of water-N,N dimethylformamide (DMF) mixtures over the whole composition range using a molecular dynamics (MD) simulation. The static and microwave frequency-dependent dielectric properties of the mixtures are calculated from MD trajectories of at least 2 ns length and compared to those of available measurements. We find that the short-ranged structural correlation between neighboring water and DMF molecules strongly influences the static dielectric properties of mixtures.

Dielectric properties of binary solvent mixtures of dimethyl sulfoxide with water.

In this paper, the dielectric properties of water-dimethylsulfoxide (DMSO) mixtures with different mole ratios have been investigated in the range of 1 GHz to 40 GHz at 298 K by using a molecular dynamics (MD) simulation. Only one dielectric loss peak was observed in the frequency range and the relaxation in these mixtures can be described by a single relaxation time of the Davidson-Cole. It was observed that within experimental error the dielectric relaxation can be described by the Debye-like model (beta approximately 1, S.