Effects of solvent on nonlinear absorption properties of tetraphenylporphyrin compounds in the nanosecond regime

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• 作者：Yong-Liang Liu^a ; ^b ; ^{liuyl593@yahoo.com.cn} ; Hui-Lan Liu^a ; Zhi-Bo Liu^b ; Wei-Ping Zang^b ; Jian-Guo Tian^b
• 关键词：Solvent effect ; Excited state absorption ; Two-photon absorption ; Tetraphenylporphyrins
• 刊名：Optik - International Journal for Light and Electron Optics
• 出版年：2012
• 期刊代码：13_00304026
• 类别：et
• 出版时间：June, 2012
• 卷：123
• 期：11
• 页码：1015-1018
• 文件大小：423 K

摘要

The nonlinear absorption properties of tetraphenylporphyrins (TPP) in different solvents and excitation intensities are investigated with nanosecond pulses by the Z-scan technique. The nonlinear absorption behaviour observed presents a distinct difference between in solvent mixtures and in pure solvents. A crossover from reverse saturable absorption (RSA) to saturable absorption (SA) and then again to RSA is observed with the increases of excitation intensity in chloroform and pyridine mixed solvents. However, porphyrin molecules in pure solvents show good RSA behaviour under the studied intensity range, no saturation absorption is observed with nanosecond excitation. Excited state absorption parameters and two-photon absorption coefficients are obtained by theoretical fit using rate equations for population densities in a seven-level energy scheme.