Solvent Dependent Absorption Properties Of Organic Dyes

• Main Authors: Li, Luo-Xin, 李洛忻
• Other Authors: Wei, Tai-Huei
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/11574512485811950633

碩士 === 國立中正大學 === 光機電整合工程研究所 === 100 === This thesis is divided into two parts. In the first part, we used the Z-scan technique with individual 16 picosecond (16 ps) laser pulse to investigate nonlinear refraction properties of (i) six individual transparent liquids (methanol, ethanol, H2O, CS2, toluene and THF) and (ii) two binary transparent liquids (methanol-ethanol and ethanol-CS2). The purpose of this study is to verify whether the interaction between the component liquids renders additional nonlinear refraction behaving as the well characterized Kerr effect. In the second part of this thesis, we used the same techniques, with both individual 16 ps laser pulses and trains of 11 16 ps pulses separated by 7 nanosecond (ns) and extending over 21ns, to investigate nonlinear absorption and refraction properties of (i) six combinations of three organic dyes and five single solvents (SiNc/ toluene, SiNc/THF, Rose Bengal/H2O, Rose Bengal/ethanol, Methyl Red/ ethanol and Methyl Red/CS2) and (ii) three combinations of three organic dyes and three binary solvents (SiNc/toluene-THF, Rose Bengal/ H2O-ethanol, Methyl Red/ethanol-CS2). The first purpose of this part of study is to verify if different single solvents affect nonlinear absorption and refractive properties of the solutes. The second purpose is to clarify if the interaction between the binary solvents induces new nonlinear absorption and refraction of these solutions. It is plausible that interaction between component solvents may introduce sequential one-photon excitation of the dye molecules and Kerr effect of the solvents in the ps regime. In addition, it may results in thermal effect in the ns regime. Via the first part of this study, we do not observe in the mixed transparent liquids additional nonlinear refraction induced by the interaction between the component transparent liquids. Via the second part of this study, we find, among the six combinations of organic dyes and single solvents, that Rose Bengal and Methyl Red show solvent dependent absorption and refraction; however, SiNc shows solvent independent nonlinear absorption and refraction. We attribute these solvent dependent nonlinear absorption and refraction to hydrogen bonds between solvents and solutes (organic dyes). Regarding the three combinations of organic dyes and binary liquids, we find that SiNc/toluene-THF does not show additional nonlinear absorption and refraction compared to SiNc/toluene and SiNc/THF. However, Rose Bengal/ H2O-ethanol, compared to Rose Bengal/H2O and Rose Bengal/ethanol as well as Methyl Red/ethanol-CS2, compared to Methyl Red/ethanol and Methyl Red/CS2, exhibit new nonlinear absorption and refraction. Regarding the three combinations of dye molecules and binary solvents, we also attribute the additional nonlinear absorption and refraction to hydrogen bonds between solvents and solutes (organic dyes).