Growth and characterization of the nonlinear optical single crystal: l-Lysinium trifluoroacetate

A novel organic nonlinear optical (NLO) crystal, l-lysinium trifluoroacetate (with the molecular formula as (H3N)+CH2CH2CH2CH2CH(H3N)+COO−CF3COO−), was grown by the controlled evaporation of its aqueous solution. The X-ray powder diffraction was used to determine its cell parameters. The calculated results based on the diffraction data reveal that l-lysinium trifluoroacetate belongs to the monoclinic crystallographic system, space group P21, with cell parameters: a = 5.698(5), b = 23.542(8), c = 8.500(6) Å, β = 91.62(9)°, V = 1139.96 Å3. The grown crystals were characterized by the elemental analyses, Fourier transform infrared and Raman spectra. Experiments of thermogravimetric (TG) and differential thermal analysis (DTA) were carried out to study its thermal properties. The optical behaviours, including transmission spectrum and second harmonic generation (SHG), were investigated to study its linear and nonlinear optical properties. Optical nonlinearities were analyzed and discussed involved with its crystal structure.