Growth and characterization of dl-Mandelic acid (C6H5CH(OH)CO2H) single crystal for third-order nonlinear optical applications

Abstract

An organic conjugated chromophore dl-mandelic acid (DLMA) single crystal was synthesized and grown-up by means of slow evaporation technique. Single crystal X-ray diffraction study proclaimed that the DLMA crystal crystallized in monoclinic system with centrosymmetric space group P21/c. The various characteristic fundamental vibration frequencies were identified by FTIR spectroscopic studies. UV–visible spectral analysis concluded that the lower cut-off wavelength and calculated direct optical band gap of DLMA as 257 nm and 5.40 eV respectively. Thermal property of dl-mandelic acid was established through thermogravimetric and differential scanning calorimetric technique. The electric field response of DLMA crystal was investigated from the dielectric studies at a few selected temperatures and frequencies. The quantum chemical assessments such as HOMO-LUMO, molecular electrostatic potential and NLO activity were calculated and presented. In order to determine mechanical strength of DLMA crystal for various loads using Vickers microhardness tester. The real and imaginary parts of the third-order susceptibility (χ3) were evaluated with the Z-scan technique using closed and open signatures respectively and was found to be Re (χ3) = 4.15 × 10−6 esu and Im (χ3) = 0.47 × 10−6 esu.