R. Gunaseelan

L-Phenylalanine L-phenylalaninium bromide – a new nonlinear optical material

L-Phenylalanine L-phenylalaninium bromide (LPLPB), an amino acid non-centrosymmetric crystal having a large second harmonic generation (SHG) efficiency, being 4.5 times that of KH2PO4 (KDP), has been successfully grown using a slow evaporation method employing a temperature gradient technique. The structure of the grown crystal was solved and refined by single-crystal X-ray diffraction, and this demonstrates that it belongs to a monoclinic system with the space group P21. The confirmation of its functional groups was recorded using Fourier transform infrared spectroscopy. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study its thermal properties. The optical behaviour was examined and its optical constants were determined by UV-vis analysis. Dielectric spectroscopy reveals the dielectric nature of the grown crystal. The mechanical strength of the grown LPLPB was estimated by microhardness studies, and the Youngs modulus of the grown LPLPB was calculated to be 3.310 × 1010 N m−2.

Unidirectional growth, rocking curve, linear and nonlinear optical properties of LPHCl single crystals

Nonlinear optical amino-acid single crystal of L-phenylalanine hydrochloride (LPHCl) was successfully grown by unidirectional Sankaranarayanan-Ramasamy (SR) method under ambient conditions for the first time. The grown single crystal was subjected to different characterization analyses in order to find out its suitability for device fabrication. The crystalline perfection was evaluated using high-resolution X-ray diffractometry. It is evident from the optical absorption study that crystal has excellent transmission in the entire visible region with its lower cut off wavelength around 290 nm.

Investigation on Growth and Surface Analysis of DAST Single Crystals

We have explored the growth of bulk size N, N‐dimethylamino‐N′‐methylstilbazolium p‐toluenesulphonate (DAST) using slope nucleation method. The grown crystal was characterized by single crystal X‐ray diffraction (XRD), and CHN analyses. The surface morphology of the crystal was analyzed using Scanning electron microscopy (SEM).

Growth, Spectral and Thermal Studies of Organic NLO Crystals of DSAS by SNM Technique

4‐N, N‐dimethylamino‐4′‐N′‐ methyl‐ stilbazolium p‐aminobenzenesulfonate (DSAS) single crystals were grown adopting slope nucleation method. Crystals of length 3 mm and diameter 0.5 mm were obtained successfully in 7 days. The elemental composition of DSAS was carried out by CHN analysis. The results are discussed in detail.