Abstract 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.

中文翻译：

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席夫碱化合物的光谱和热非线性研究

摘要 通过4-氨基苯甲酸与2, 4-羟基苯甲醛缩合反应，成功合成了席夫碱化合物2, 4-羟基-4-羧基苄基苯胺(C14H11NO4)。官能团已通过傅里叶变换红外光谱 (FTIR) 分析得到证实。核磁共振 (NMR) 光谱用于确定质子在获得的化合物中的位置。在室温下获得了该化合物的紫外-可见吸收光谱。当用波长为 473 nm 的连续波激光束照射席夫碱化合物时，观察到衍射环图案。获得的图案类型取决于激光束波前的类型。基于环的数量，获得了复合折射率和非线性折射率的总变化。使用 Fresnel-Kirchhoff 衍射理论成功模拟了实验衍射环图案，实验结果与理论结果之间具有良好的定性和合理的定量一致性。分别进行开孔和闭孔 Z 扫描以测量席夫碱化合物的非线性吸收系数和非线性折射率。也测试了席夫碱化合物的光学限制行为。分别进行开孔和闭孔 Z 扫描以测量席夫碱化合物的非线性吸收系数和非线性折射率。也测试了席夫碱化合物的光学限制行为。分别进行开孔和闭孔 Z 扫描以测量席夫碱化合物的非线性吸收系数和非线性折射率。也测试了席夫碱化合物的光学限制行为。