Nonlinear optical characteristics of N,N’-bis(salicylidene)-p-phenylenediamine: Z-scan technique and quantum mechanical calculations

ABSTRACT. In this work, we have characterized the linear and nonlinear optical properties of N,N′-bis(salicylidene)-p-phenylenediamine (BSP) in both macroscopic and microscopic modes by using Z-scan technique and quantum chemical calculations. The microscopic nonlinear optical properties of BSP were investigated by density functional theory with the basis set of 6-311G++dp. Electronic properties such as frontier molecular energies, band-gap energy, electron affinity, hardness, softness, and ionization potential were evaluated. The calculation of microscopic quantities included first-order hyperpolarizability and natural bond orbitals showed the electron delocalization, which confirmed the nonlinear optical properties in this compound. The results of the absorption spectrum of BSP in DMSO, DMF, CH3Cl solvents were shown that the dissolved sample in DMSO had better nonlinear properties than others. Then the macroscopic nonlinear properties of the sample were determined by the Z-scan technique. The values of the nonlinear refractive index (n2), nonlinear absorption coefficient (β), and third-order nonsusceptibility of the sample in DMSO were, 0.09250×10-10 cm2/W, -0.174×10–6 cm/W and 4.101× 10-5 esu, respectively. The two-photon absorption in this molecule has been enhanced by the donor–bridge–donor (D–π–D) architecture. The theoretical and experimental results concluded that BSP seems to be promising candidates for future photonic and optoelectronic devices.                 KEY WORDS: Azo dye, Nonlinear optic, Hyperpolarizability, One photon absorption, Two photon absorption, Schiff bases   Bull. Chem. Soc. Ethiop. 2022, 36(2), 465-477.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i2.18                                                       &nbsp