Spectral, nonlinear optical and optical limiting properties of l-phenylalanine l-phenylalaninium formate single crystal.

l-Phenylalanine l-Phenylalaninium Formate (LPPF) is an organic nonlinear optical crystal with molecular formula C9 H11 NO2 ·C9 H12 NO2 + ·CHO2 - , was grown by solution growth, slow evaporation method. Single crystal XRD reveals that the title compound crystallizes in monoclinic system with the space group P21. The presence of functional groups was identified by FT-IR spectrum. UV-visible spectrum analysis shows that the crystal exhibits good optical transparency with a minimum cut-off wavelength of 200 nm. Refractive index of the crystal was measured as 1.6408 by using prism coupling technique. The Dielectric constant and dielectric loss were studied as a function of frequency at different temperatures and also activation energies were measured at different frequencies. The melting point of LPPF was found as 276.37 °C by TG-DSC analysis. Second order NLO efficiency was estimated by Kurtz Perry Powder technique. Third order NLO properties like nonlinear absorption coefficient (β), nonlinear refractive index (n2) and third order nonlinear susceptibilities (χ3 ) were measured with femto second pulsed laser using Z Scan technique. From third order NLO studies it is noticed that the material exhibiting strong reverse saturable absorption which is an essential requirement for passive optical limiting application.