Third-order NLO studies of 2, 4-Bis (4-fluorophenyl)-2, 3-dihydro-1H-1, 5-benzodiazepine using Z-scan technique and DFT method

Abstract

The present work discusses the nonlinear optical properties of 2, 4-Bis (4-fluorophenyl)-2, 3-dihydro-1H-1, 5-benzodiazepine. The structural characterizations have been performed using FT-IR, FT-Raman, and UV-Visible absorption spectroscopic techniques. The optimized geometry, vibrational wavenumbers, natural bond orbital analysis, HOMO-LUMO analysis, natural population analysis were calculated using the B3LYP/6-311++G (d, p) level of theory. Unambiguous vibrational assignments have been performed using potential energy distribution values obtained from normal coordinate analysis using MOLVIB program. The theoretical second-order hyperpolarizability was calculated using B3LYP and CAM-B3LYP hybrid functional at the DFT level. The second-order hyperpolarizability (γ),third-order susceptibility (χ(3)), nonlinear refractive index (n2), nonlinear absorption coefficient (β)) have been investigated using the Z-scan technique. The Z-scan results confirm that the compound exhibits positive nonlinear absorption and negative nonlinear refractive index. The second harmonic generation efficiency was investigated using the Kurtz and Perry method and was found to be 1.44 times higher than urea. The obtained results reveal that the title compound is a promising material for laser assisted applications.