Optical nonlinearity and charge transfer analysis of 4-[(E)-2-(2,4,6-Trinitrophenyl) ethylidene] benzonitrile adsorbed on silver nanoparticles: Computational and experimental investigations

The search for a potential nonlinear optical (NLO) material has led to the investigation of an organic compound 4-[(E)-2-(2,4,6-Trinitrophenyl)ethylidene]benzonitrile (TEB), which has a possibility of enhancing the NLO properties by the charge transfer mechanism if metal atoms are adsorbed on it. The experimental characterization of TEB is done using Fourier Transform Infrared (FT-IR), Fr-Raman, Ultraviolet-visible (UV-Visible), Photoluminescence (PL), Thermogravimetric/Differential Thermal Analysis (TG/DTA) and Z-scan techniques. The third order NLO properties evaluated using Z-scan technique proves that the material can be used as a good optical limiter. TEB is attached with silver atoms and the theoretical studies including geometry optimization, NBO analysis and hyperpolarizability calculations are carried out. The TEB molecule with silver atoms adsorbed is found to have increased hyperpolarizability values. The charge transfer from the metal atom to the nitrile group of the molecule is evident from the Surface Enhanced Raman Scattering (SERS) spectra using the silver nanoparticles. (C) 2018 Elsevier Ltd. All rights reserved.