Optical, structural, thermal, mechanical and third-order nonlinear optical properties of 2-nitroanilinium bromide single crystal: Experimental and theoretical approach

The centrosymmetric third-order nonlinear optical organic single crystal of 2-nitroanilinium bromide (2NAB) was grown by slow evaporation solution growth technique at 30-40 degrees C temperature using ethanol as the solvent. The crystal structure of the grown crystal has been determined by single-crystal X-ray diffraction analysis and it belongs to orthorhombic crystal system with centrosymmetric space group Pbca. The optimized geometrical parameters were theoretically calculated by the DFT/B3LYP/6-311G(d,p) method and compared with experimental values. FTIR and FT-Raman analysis was carried out to identify the functional groups of the grown crystal. The NMR chemical shift of the 2NAB molecule was calculated by the GIAO (Gauge Independent Atomic Orbital) method and compared with experimental results. The UV-Visible spectrum was carried out and the optical band gap energy was found to be 4.6 eV. The thermal behaviour of the grown crystal was analysed by thermal gravimetric-differential thermal-differential scanning calorimetric analysis (TG-DTA-DSC). This shows that there are no weight losses up to 108 degrees C. Vickers microhardness analysis was carried out to identify the mechanical stability of the grown crystal. Red emission takes place at 722 nm was identified from photoluminescence study. Laser damage threshold energy has been measured by using Nd:YAG laser. The third-order nonlinear optical property of grown crystal was investigated by Z-scan technique with Nd:YAG laser radiation, and the corresponding nonlinear refractive index and absorption coefficients were also calculated.