Spectroscopic and thermal nonlinearity study of a Schiff base compound

Schiff base compound 2, 4 hydroxy-4- carboxy benzylidene aniline (C14H11NO4) was successfully synthesized by condensation reaction of 4-amino benzoic acid and 2, 4-hydroxy benzaldeyhyde. The functional groups have been confirmed via Fourier-transform infrared spectroscopy (FTIR) analysis. The Nuclear magnetic resonance (NMR) spectroscopy was used to identify the placement of protons in the obtained compound. UV-visible absorption spectrum was obtained at room temperature for the compound. Diffraction ring patterns were observed when the Schiff base compound was irradiated with a continuous wave laser beam of wavelength 473 nm. The type of the obtained patterns depends on the type of the laser beam wave front. Based on the number of rings the total change in the compound refractive index and the nonlinear refractive index were obtained. The experimental diffraction ring patterns were successfully simulated using the Fresnel-Kirchhoff diffraction theory with good qualitative and reasonable quantitative agreements between experimental and theoretical findings. Both the open and closed aperture Z-scans were performed to measure the nonlinear absorption coefficient and nonlinear refractive index of the Schiff base compound, respectively. The optical limiting behavior of the Schiff base compound was tested too.