Semiorganic nonlinear optical L-lysine sulphate growth and characterization

L-lysine sulphate (LLS), a semiorganic nonlinear optical (NLO) material useful for frequency doubling in the IR region, has been synthesized. The solubility studies have been carried out in the temperature range 30-50 degrees C. Single crystals have been grown by slow evaporation method from an aqueous acetone solution of l-lysine and sulphuric acid. The grown crystals were bulk, bright and transparent. These crystals were characterized by X-ray and FTIR studies. Powder X-ray pattern indicates that LLS crystallizes in orthorhombic space group P2(1)2(1)2(1) with four unit cells. FTIR spectral studies were performed for the conformation of the l-lysine molecule and hydrogen bonds. The optical transmission spectra of the grown crystal are tested by UV-vis spectrophotometer and found that the crystal was transparent over entire visible region. The second harmonic generation test of the LLS revealed the nonlinear nature of the crystal.