IR, Raman and surface-enhanced Raman scattering (SERS) spectra of L-proline were recorded and analyzed. The molecular plane assumes a tilted orientation with respect to the metal surface. The vibrational wavenumbers and corresponding vibrational assignments are examined theoretically using the Gaussian 03 set of quantum chemistry codes.

FT-IR and FT-Raman spectra of hirudin have been recorded from the native solid hirudin. The conformation of the molecule has been discussed on the basis of IR and Raman data. It has been concluded that hirudin molecule has a mired alpha -helix and random coil conformation.

FT-IR and FT-Raman spectra of ethyl methyl ketone semicarbazone were recorded and analyzed. The vibrational wavenumbers were computed using HF/6-31G*, B3PW91/6-31G* and B3LYP/6-31G* basis and compared with experimental data. The first hyperpolarizability, infrared intensities and Raman activities are reported. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of non-linear optics. The extended p-electron delocalization over the carbazone moiety is responsible for the nonlinearity of the molecule. The geometrical parameters of the title compound are in agreement with that of similar derivatives. The red shift of the NH stretching wavenumber in the infrared spectrum from the computed wavenumber indicates the weakening of the NH bond resulting in proton transfer to the neighboring oxygen atom.

Objective: The use of HEMA as a biocompatible material in dentin bonding systems and its potential for clinical applications has been well established. Excess water can affect conversion of bonding resins. The aim of this study was to survey the effect of water on the degree of conversion of HEMA by Fourier Transform Infra-red Spectroscopy (FT-IR).Materials and Methods: In this experimental study, distilled water was added in amounts of 0, 0.05, 0.1, 0.2, and 0.4 ml to 1 ml of curable HEMA solution. Six repetitions per wa-ter ratio were made and investigated. Each sample was polymerized for 60 seconds. De-gree of conversion was obtained from the absorbance IR-Spectrum of the materials before and after polymerization by FT-IR spectroscopy. One way ANOVA and Tukey-HSD were carried out to compare and detect any differences among groups. Results: Statistical analysis indicates highly significant difference between pairs of groups at level (P<0.001). The results showed a trend of decreasing in HEMA conversion with increasing water. Degree of conversion changes significantly within the 0.05 ml to 0.2 ml water range. However, degree of conversion did not change after reaching 0.02 ml and before 0.05. Conclusion: Degree of conversion of HEMA decreased by increasing water. The most dramatic effect of water on the polymerization process occurs within a range which exists under clinical conditions. The reason that the degree of conversion did not show signifi-cant result before 0.05 ml may be related to the hydrophilic nature of HEMA.

Di-2-pyridyl ketone nicotinoylhydrazone was prepared by condensation between appropriate aldehyde/ketone with the respective acid hydrazide. The FT-IR spectrum is recorded and analysed. The vibrational frequencies were computed using the HF/6-31G(d) and B3LYP/6-31G(d) basis and compared with experimental data. The infrared intensities and first hyperpolarizability are reported. The calculated data suggest an extended π-electron delocalization over the pyridyl and nicotinoyl hydrazone moieties which are responsible for the nonlinearity of the molecule. Optimized geometrical parameters (DFT) of the title compound are in agreement with similar reported structures.

In this work, the experimental and theoretical study on molecular structure and vibrations of 2, 6-Lutidine (2, 6-Ltn) are presented. The FTIR and FTRaman experimental spectra of the 2, 6-Ltn have been recorded in the range of 4000-100 cm-1 . Making use of the recorded data, the complete vibrational assignments are made and analysis of the observed fundamental bands of molecule is carried out. The experimental determinations of vibrational frequencies are compared with those obtained theoretically from ab initio HF and DFT quantum mechanical calculations at HF/6-31+G (d, p), B3LYP/6-31++G (d, p) and B3LYP/6-311++G (d, p) levels. The differences between the observed and scaled wave number values of most of the fundamentals are very small in DFT. The geometries and normal modes of vibrations obtained from ab initio HF and B3LYP calculations are in good agreement with the experimentally observed data. Comparison of the simulated spectra provides important information about the ability of the computational method (B3LYP) to describe the vibrational modes. The vibrations of couple of CH3 groups with skeletal vibrations are also investigated.