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 C₉H₁₁NO₂·C₉H₁₂NO₂⁺·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 P2_1. 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.