Synthesis Of Gold Nanorods And Research Of Localized Surface Plasmon Enhanced Up-conversion

Up-conversion materials are attracting attention in many areas.Due to small phonon energy,low multi-phonon relaxation rate and other advantages,NaYF4 nanoparticles(NPs)are considered to be the most effective matrix material.At present,there are two main phases of NaYF4 NPs:tetragonal a-NaYF4 and hexagonal ?-NaYF4.The luminescent performance of ?-NaYF4 is superior to that of a-NaYF4.Therefore,hexagonal ?-NaYF4 NPs was used as host material in this paper.The up-conversion of?-NaYF4:Er3+,Yb3+ NPs and the Localized Surface Plasmon Resonance(LSPR)enhancement effect of gold nanorods on up-conversion were investigated.Firstly,Er3+-Yb3+ co-doped up-conversion NPs were prepared by coprecipitation method.At the same time,short gold nanorods(Au SRods)and long gold nanorods(Au LRods)were prepared by seed-mediated growth method.Then,the gold nanorods were coated silica by using the Stober method.Secondly,different concentrations of Au SRods and Au LRods were mixed with ?-NaYF4:Er3+,Yb3+ up-conversion NPs,respectively.The plasmon enhanced up-conversion luminescence was achieved attributed to the LSPR of gold nanorods,which will enhance the up-conversion excitation and emission.When the molar ratio of Au SRod and p-NaYF4:Er3+,Yb3+ NPs was 0.03%,the enhancement effect was strongest.When the molar ratio of Au LRod and the p-NaYF4:Er3+,Yb3+ NPs was 0.05%,the enhancement effect was strongest.Finally,different shell thickness of Au LRod@SiO2 was also synthesized.Then,Au LRod@SiO2 and ?-NaYF4:Er3+,Yb3+ NPs were mixed and diluted in a certain proportion.The plasmon enhanced up-conversion of?-NaYF4:Er3+,Yb3+ NPs with single Au LRod@SiO2 nanorod was investigated through micro-region fluorescence spectroscopy.The optimal enhancement effect was obtained when the coating thickness of SiO2 was 25nm.