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Both THz-TDS and NMR techniques were employed to study the hydrogen bonding networks formed in 2-propanol/water mixtures. The composition of such solvent mixtures is shown to significantly impact on the mobility of the solute molecules.
Terahertz absorption spectra of Poly(3-hydroxybutyrate)s were measured. The orientation of the transition dipole moment was investigated by the polarization spectra. The temperature dependence of the spectra reflects the change in the hydrogen bonding distance of the crystalline structure.
Differences in the terahertz spectral features and the assignment of terahertz absorptions and hydrogen bond networking of tyrosines were examined. The inter- and intra-molecular absorptions in a terahertz region were calculated by the structural optimization simulation “Gaussian 03” at B3LYP/6-31G (d) level using the mid-IR absorptions.
We demonstrate THz nonlinearity of liquid water revealed with intense monocycle THz pulse. Single THz pulse response and THz pump-probe spectroscopy show the breaking and recovering of hydrogen bonding network in water molecules.
The vibrational spectra of water clusters in the gas phase are calculated by using Ab initio calculation and molecular dynamics. The result reveals that the non-chiral water molecules have circular dichroism (CD) effect due to the hydrogen bondings between the molecules. Strong absorption and circular dichroism have been observed in THz range.
The THz absorption of the intermolecular vibrational modes of the hydrogen bond network of water has recently been found to define a dynamical solvation shell around solutes that extends beyond the first hydration layer. Here, we study the vibrations and dynamical processes in the hydrogen bond network of water using molecular dynamics (MD) simulations to understand its properties.
Single frequency coherent terahertz-wave generation method is used to obtain low-frequency spectra of the hydrogen bonding organic small molecules. Transmission spectrum of each sample show several peaks in this region. On the other hand, ab initio frequency calculations are performed for each molecule by CRYSTAL06 package. Both experimental results and theoretical calculations are compared each other.
Due to its inherent sensitivity to both subtle changes in crystal structure and the hydrogen bonding network of organic molecular crystals and moisture, terahertz time-domain spectroscopy (THz-TDS) is a very promising technique to study physico-chemical changes during stability testing of pharmaceutical dosage forms. Using a variable temperature and humidity chamber the effects of moisture and temperature...
We combined experimental terahertz time-domain spectroscopy (THz-TDS) and ab-initio simulation based on density functional theory to predict with a large confidence the THz vibration spectrum of molecules in the crystalline phase. The results demonstrate two kinds of vibration modes. One is a pure inter-molecular hydrogen bonding vibration mode, and the other is dominated by inter-molecular and intramolecular...
We measured the dynamics of aqueous biomaterial mixtures using terahertz time-domain spectroscopy. The mixtures were divided into water and other electrolyte parts in mass fractions for analysis. The optical constants of the electrolytes, excluding water, were obtained by applying the ideal mixture equation and fitted with the modified double Debye model. We found that the reorientation and hydrogen-bond...
Using THz time-domain and FTIR spectroscopy we measure the far-infrared absorption spectra of various biomolecular crystals with different numbers of hydrogen bonds of different strengths. The experimental data are compared to density functional theory calculations.
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