Synthesis and third order optical nonlinearity studies of toluidine tartrate single crystal supported by photophysical characterization and vibrational spectral analysis

Abstract

The organic nonlinear crystal Toluidine Tartrate (TT) was synthesized, its structure was reinvestigated by X-ray diffraction analysis and investigated theoretically as well as experimentally to examine its nonlinear optical (NLO) behavior. The electron transport mechanism and hydrogen bonding interactions in TT have been explored using the Natural Bond Orbital analysis and optimized geometry calculations. The vibrational spectral investigations of the compound have been carried out using the experimental and computational FT-IR and FT-Raman analyses. UV–vis spectral investigations show the optical absorption of TT crystal at 271 nm and 319 nm and reveal its optical transparency in the visible region. The HOMO LUMO study reveals a 4.5388 eV energy gap which shows its reactivity. Photoluminescence and lifetime studies show a near violet emission with considerable lifetime. The thermal property of the sample was analyzed by TG and DTA analysis and it was found that the TT crystalline compound is stable up to 201 °C. Hyperpolarizability calculations give an augmented value of hyperpolarizability. Z-scan measurements in the pulsed as well as continuous wave laser excitation regimes reveal a substantial decrease in normalized transmittance at higher laser fluences, substantiating the nonlinear behavior and optical limiting application of TT crystals.