Growth and characterization of an organic NLO material ammonium malate

Second harmonic generation organic material, ammonium malate (AM), has been synthesized and grown as quality single crystals by the slow evaporation technique. As-grown crystals were characterized by Xray powder diffraction (XRPD) and Fourier transforms - nuclear magnetic resonance (FT-NMR). The optical hand gap was estimated for AM crystal using UV-vis study. Measuring transmittance of AM permitted the calculation of the refractive index n; the extinction coefficient K and both the real epsilon(r) and imaginary Pi components of the dielectric permittivity as functions of photon energy. Density functional theory at the HF/3-21 G (d, p) level has been used to calculate the first-order hyperpolarizability of AM. The second harmonic conversion efficiency of AM was determined using Kurtz powder technique; it was observed to be greater than that of KDP. The mechanical anisotropy property of the grown crystals was studied using Vickers microhardness tester at different planes. The photoluminescence study is also analyzed. The growth features were analyzed by wet chemical etching studies. The factor group analysis was carried out for AM which predicts that there are 132 vibrational optical modes. (C) 2009 Elsevier B.V. All rights reserved.