Characterization of l-threonine phthalate crystal for photonic and nonlinear optical applications

l-Threonine phthalate (LTP) single crystal, an organic nonlinear optical material, has been synthesized and grown by slow evaporation technique at room temperature. The lattice parameters of the grown crystal have been determined using single crystal X-ray diffraction data. It crystallizes in the monoclinic system with space group C2/c. The optical parameters: transmission range, extinction coefficient, refractive index and reflectance of the grown crystal were estimated from UV–vis–NIR spectral data. The steady-state photoluminescence spectra were recorded for l-threonine phthalate crystal at room temperature. The photoluminescence peaks show that the LTP crystal has strong ultraviolet and red emissions at 306 nm and 612 nm, respectively. The molecular weight of the new crystal has been ascertained from mass spectroscopic analysis to confirm the formation of the new crystal. The dielectric study of the sample was carried out in the frequency range from 50 Hz to 5 MHz. The mechanical properties of the grown crystal were analysed using Vickers microhardness tester. Since pure l-threonine is capable of generating second harmonic generation, phthalic acid doped l-threonine crystal is unable to generate second harmonic generation due to centrosymmetric nature. Z-scan technique was finally used to analyse third order NLO property.