SECOND-ORDER NONLINEAR OPTICAL PROPERTIES OF TITANIUM DIOXIDE NANOPARTICLES AND NANOPARTICLES-DYE COMPOSITES |
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Authors: | Wang Xin Zhang Yü Deng Hui-hua Shen Yao-chun Lu Zu-hong Cui Yi-ping |
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Institution: | National Laboratory of Molecular and Biomolecular Electronics, Southeast University, Nanjing 210096, China; Laboratory of Optoelectronic Technology, Southeast University, Nanjing 210096, China |
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Abstract: | Hyper-Rayleigh Scattering (HRS) technique was used to study the second-order nonlinear optical (NLO) responses of aqueous titanium dioxide (TiO2) nanoparticles of 10nm in size, and two nanoparticles-dye composites prepared by adding rhodamine B (Rh610) or the organic tosylate salt of dimethylaminostilbazolium (DAST). Results showed that the "per particle" first hyperpolarizability β for TiO2 nanoparticles is very large, in the range of 1026 esu. With adding Rh610 and DAST, the HRS signals of the composites were further enhanced. And in TiO2/Rh610 composite the enhancement was obviously greater than that of TiO2/DAST composite. It has proved that non-centrosymmetry of the nanocrystal/solution interface contributes mainly to its large "per particle" β, overwhelming the nanocrystal core. So the interactions between nanoparticles surfaces and adsorbed dyes were very important for their second-order NLO responses. HRS technique provides a useful new NLO method to characterize the surface structures and microenvironment of nanoscale materials. |
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Keywords: | nanoparticle nanoparticle-dye composites hyper-Rayleigh scattering (HRS) first hyper-polarizability (β) nonlinear optics |
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