Third-order NLO properties and optical limiting behavior of p-toluidinium 2,4-dichlorobenzoate organic single crystal

This research work focuses on the synthesis and characterization of p-toluidinium 2,4-dichlorobenzoate (PTDA), organic non-linear optical crystal grown at room temperature. Single crystal X-ray diffraction (SCXRD) analysis was used to analyze the lattice parameters under the centrosymmetric space group of P121/c1 with a monoclinic crystal system. The crystalline nature and phase identification of the sample was analyzed by powder X-ray diffraction (PXRD) analysis. FT-IR and ¹H NMR were used to identify the functional groups and various vibrations present in the grown crystal. The cut-off wavelength was observed at 284 nm from the transmittance spectrum, and the optical bandgap value (4.06 eV) was also determined from UV-visible analysis. TG-DTA analysis was carried out to understand its thermal properties. The mechanical strength of the material plays an important role in fabricating devices. Open-aperture Z-scan analysis was taken in order to get its third-order nonlinearity using Nd: YAG nanopulsed laser. PTDA crystal exhibits reverse saturable absorption and shows two-photon absorption- induced optical limiting behavior. Theoretical calculations were done by using Gaussian 09 software with a basic set of B3LYP/6-311G++ (d, p) to provide optimized molecular geometry, Frontier Molecular Orbital (FMO), and NBO analysis.