Nonlinear optical single crystals of L-cysteine hydrochloride monohydrate (LCB) were grown by slow evaporation technique. Single crystal X-ray diraction analysis revealed the crystal system and helped to determine lattice parameter values. Powder X-ray diraction analyses were carried out and the diraction patterns were indexed. The optical properties of the crystals were determined using UV-visible spectroscopy. Optical constants such as refractive index, extinction coecient and electric susceptibility were determined from UV-visible spectroscopy. The Fourier transform infrared studies conrmed the various functional groups present in the grown crystal. The mechanical behaviour of the grown crystals was studied using Vicker's microhardness tester. The thermal analysis conrmed that the crystal was stable up to 108.7• C. The dielectric constant and the dielectric loss measurements were carried out for dierent temperatures and frequencies. Second harmonic generation of LCB crystal was investigated by the Kurtz powder technique.

In the title compound, C12H12O4, the hydr­oxy O and the C and O atoms of the acetyl group are almost coplanar [maximum deviation = 0.0356 (1) Å] with the benzene ring. The dihedral angle between the benzene ring and the plane through the non-H atoms of the methacrylo­yloxy group is 86.1 (1)°. In the crystal structure, mol­ecules are linked by two C—H⋯O hydrogen bonds, forming dimers with graph-set descriptor R 2 2(16). A strong intra­molecular O—H⋯O hydrogen bond is also observed.

Abstract-In the present work, L-Cysteinium Sodium NitrateChloride (LCSNC) an organic nonlinear optical material has been synthesized by a slow evaporation method. The crystalline nature was confirmed by single crystals X-ray diffraction analysis. The UV-Vis transmittance spectrum shows that the crystal has a good optical transmittance in the entire visible region with lower cutoff wavelength 203 nm. The various functional groups and chemical compositions of the grown crystal have been derived from FTIR spectral analysis. Both dielectric constant and dielectric loss decrease with an increase in frequency. The SHG efficiency was measured by employing the powder Kurtz method.The search for new materials with high optical nonlinearity is an important area due to their applications like optical communication, optical computing, optical information processing, optical disk data storage, laser fusion reactions, laser remote sensing, colour display, medical diagnostics, and so forth [1][2]. Most of the organic NLO crystals usually have poor mechanical and thermal properties and are susceptible to damage during processing even though they have large NLO efficiency. Purely inorganic NLO materials have excellent mechanical and thermal properties but possess relatively modest optical non linearity because of the lack of extended pi-electron delocalization. Organic NLO materials are often superior to inorganic in terms of their response speed, optical clarity, and the magnitude of their third order susceptibility. However, for a material to exhibit NLO activity it should be noncentrosymmetric. Also organic materials have a high nonlinear optical coefficient, higher laser damage threshold, fast response, low mobility, and their large band gap finds many applications [3][4].L-cysteine is an organic compound under an amino acid category. It is one of the naturally occurring protenogenic amino acids. L-cysteine exists in a zwitterionic form; the molecule can combine with anionic, cationic and overall neutral constituents. In this paper we report the growth, structural, vibrational, optical, dielectric, and second harmonic generation (SHG) * E-mail: jap.azee.phy@gmail.com properties of single crystals of L-cysteinium sodium nitrate chloride (LCSNC).The material was synthesized by taking L-cysteine and sodium nitrate in a 1:1 stoichiometric ratio.A calculated amount of these materials was taken and dissolved in deionized water then hydrochloric acid was added drop by drop to reduce pH less than 2, then the solution was filtered by a Whatmann filter paper of the 11μm pore size [5]. The prepared solution was allowed to dry at room temperature and the salts were obtained by a slow evaporation technique. The purity of the synthesized salt was further improved by a successive recrystallization process yielding a crystal of the size 21×7×9mm 3 in a growth period of 27 days. The grown single crystal of LCSNC is shown in Fig. 1. The single crystal X-ray diffraction analysis of the crystal indicates that it crystallizes in a monoclinic sys...