Growth and characterization of organic material 4-dimethylaminobenzaldehyde single crystal.

The organic material 4-dimethylaminobenzaldehyde single crystals were grown by slow evaporation technique. The grown crystal was confirmed by the single crystal and powder X-ray diffraction analyses. The functional groups of the crystal have been identified from the Fourier Transform Infrared (FTIR) and FT-Raman studies. The optical property of the grown crystal was analyzed by UV-Vis-NIR and photoluminescence (PL) spectral measurements. The thermal behavior of the grown crystal was analyzed by thermogravimetric (TG) and differential thermal analyses (DTA). Dielectric measurements were carried out with different frequencies by using parallel plate capacitor method. The third order nonlinear optical properties of 4-dimethylaminobenzaldehyde was measured by the Z-scan technique using 532 nm diode pumped continuous wave (CW) Nd:YAG laser.

Molecular structure, NBO analysis, electronic absorption and vibrational spectral analysis of 2-Hydroxy-4-Methoxybenzophenone: reassignment of fundamental modes.

Vibrational frequencies of 2-Hydroxy-4-Methoxybenzophenone (HMB) have been reassigned with the aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The conformational analyses were performed and the energies of the different possible conformers were determined. The geometry of different conformers of the compounds were optimized with B3LYP method using 6-311++G(d,p) basis set to characterize all stationary points as minima. The optimized structural parameters of the most stable conformer were used in the vibrational frequency calculations. The force constants obtained from the B3LYP/6-311++G(d,p) method have been utilized in the normal coordinate analysis. The temperature dependence of the thermodynamic properties, heat capacity at constant pressure (Cp), entropy (S) and enthalpy change (ΔH) for the compound was also determined by B3LYP/6-311++G(d,p) method. The total electron density and Molecular electrostatic potential surfaces of the molecules were constructed by Natural Bond Orbital analysis using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron+nuclei) distribution, molecular shape, size, and dipole moments of the molecule. The electronic properties, HOMO and LUMO energies were measured.

Three-photon absorption and vibrational spectroscopic study of 2-methylamino-5-chlorobenzophenone.

In this paper, the vibrational spectral analysis and three-photon absorption properties of an organic material of 2-methylamino-5-chlorobenzophenone have been reported. The geometry and harmonic vibrational wavenumbers are calculated with the help of B3LYP density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of normal coordinate analysis following the scaled quantum mechanical force field methodology (SQM). SQM force fields have also been used to calculate potential energy distribution (PED) in order to make conspicuous vibrational assignments. The nonlinear absorption properties have been investigated in ethanol solution at 532nm using the Z-scan technique employing laser pulses of 5ns duration. Open aperture Z-scan data reveal the presence of effective three-photon absorption for ns pulses at 532nm resulting in a strong optical limiting behavior, indicating possible photonic applications.

Growth and characterization of organic material 3-hydroxybenzaldehyde single crystal by modified vertical Bridgman technique.

Novel organic nonlinear optical (NLO) material 3-hydroxybenzaldehyde (3HBA) single crystals have been grown by modified vertical Bridgman technique using the single and double wall ampoules with nano translation. Single crystal X-ray diffraction analysis reveals that 3HBA crystallizes in orthorhombic system and the powder X-ray diffraction (XRD) pattern was indexed. Fourier transform infrared studies confirm the functional groups of the crystal. The optical property of the grown crystal was analyzed by UV-vis-NIR and photoluminescence (PL) spectral measurements. The thermal property of the grown crystal was analyzed by thermogravimetric (TG) and differential thermal analyses (DTA). The dielectric measurements were carried out with four different frequencies at various temperatures ranging from 308 to 373K and the results indicate an increase in dielectric parameters with the increase of temperature at all frequencies. The NLO property of 3HBA was analyzed by second harmonic generation (SHG) studies.

Growth and characterization of organic material 2-methylamino-5-chlorobenzophenone single crystal by modified vertical Bridgman technique.

The organic material 2-methylamino-5-chlorobenzophenone single crystal has been grown by modified vertical Bridgman technique using the single wall ampoule with nano translation. The grown crystal was confirmed by single crystal and powder X-ray diffraction analyses. Fourier transform infrared analysis was used to identify the functional groups present in the grown crystal. High resolution X-ray diffraction studies show the crystalline perfection of the grown crystal. The optical property of the grown crystal was analyzed by UV-vis-NIR and photoluminescence spectral studies. The thermal behavior of the grown crystal was analyzed by thermogravimetric and differential thermal analyses. The dielectric measurements of the grown crystal were carried out with different frequencies and temperatures and the results indicate an increase in dielectric and conductivity parameters with the increase of temperature at all frequencies. The microhardness measurements were performed to analyze the mechanical property of the grown crystal.

Growth and characterization of 2-hydroxy-4-methoxybenzophenone single crystal using modified vertical Bridgman technique.

The 2-hydroxy-4-methoxybenzophenone single crystal has been grown by the modified vertical Bridgman technique using the double wall ampoule. The grown crystal was confirmed by single and powder X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analyses. High resolution X-ray diffraction (HRXRD) analysis indicates the crystalline perfection of the grown crystal. The cutoff wavelength of the grown crystal was analyzed by optical studies. The dielectric measurements were carried out and the results indicate an increase in dielectric and conductivity parameters with the increase of temperature at all frequencies. The thermal property of the grown crystal was studied by thermo gravimetric (TG) and differential thermal analyses (DTA).

Brain surface electrode co-registration using MRI and X-ray.

Electrocorticographic recording is now being used in a wide variety of experimental settings. We present a simple method which can be used to estimate electrode position with respect to brain gyral anatomy using a pre-implantation MRI and post-implantation coronal and sagittal x-rays. It is semi-automated, with the user manually rotating and scaling an x-ray to fit brain outline, identifying threshold values for brain surface rendering, and clicking on electrodes on an x-ray. Electrode positions can be rapidly identified and rendered in about 20 minutes from start to finish. This approach is useful when the MRI quality is poor, there is no quality CT, but one would like to understand the relationship between experimental result and brain anatomy.

Growth and characterization of naphthalene single crystals grown by modified vertical Bridgman method.

The large size 20 mm diameter naphthalene single crystals were grown by modified vertical Bridgman method. The optical quality of the grown crystal was analyzed by photoluminescence and ultraviolet visible absorption spectral measurements. Photoluminescence spectrum indicated violet emission at 410 nm. The UV-vis absorption spectrum shows the maximum at 219.32 nm. The microhardness measurements and differential thermal analysis performed to analyze the mechanical and thermal stability of the as grown crystals. The dielectric measurements were carried out at five frequencies, viz., 100 Hz, 1 kHz, 10 kHz, 100 kHz and 1 MHz and at various temperatures, ranging from 308 K to 348 K indicate an increase of the dielectric parameters with the increase of temperature at all the five frequencies. The conductivity of the material is understood to be more of electronic in nature. Also, the increase in the dielectric parameters with that of temperature is due to the temperature variation of electronic polarizability.