Chemical analysis, FTIR and microhardness study to find out nonlinear optical property of L-asparagine lithium chloride: a semiorganic crystal

摘要

In recent times semiorganic nonlinear optical material is a forefront of current research because of its importance to providing key functions of frequency conversion, light modulations and optical memory storage. Most of the organic materials have inadequate transparency, poor optical quality and low laser damage threshold. Inorganic materials have excellent mechanical and thermal properties but they possess relatively modest nonlinearity.Semiorganicmaterialswhich have combined properties of both organic and inorganic materials. In this coordination complex the organic ligand plays an important role for the nonlinear optical property. Nowadays, amino acids are more suitable organic materials for nonlinear optical applications because they contain dipolar nature due to the presence of a protonated amino group (NH_3 ~+) and deprotonated carboxylic group (COO~-). In the present study L-asparagine lithium chloride (LALC) was grown from aqueous solution by slow evaporation method. The crystalline perfection of thematerialwas confirmed by powder X-ray diffraction. The lattice parameterswere calculated by single crystal X-ray diffraction and it was found to be the LALC crystallized in orthorhombic crystal systemwith noncentro symmetric space group of Pna2_1 which is one of the essential parameters in nonlinear opticalmaterials. The optical transparencywas analyzed by UV-vis transmission spectral study and itwas found to be of lower cut offwavelength of the grown crystalwhich is 234 nm. The presence of functional groups was identified by FTIR spectral analysis. The percentage of carbon, hydrogen and nitrogen in the crystal was calculated by chemical analysis and compared with its theoretical values. The mechanical strength was calculated by Vickers microhardness tester. The nonlinear optical efficiency of the crystal was estimated by using Kurtz Perry powder technique and it was found to be 2.08 times that of potassium dihydrogen phosphate (KDP) due to noncentro symmetric space group of good nonlinear opticalmaterial. Hence, LALC crystal ismore suitable for the fabrication of optoelectronic devices.