The Study Of Fluorescence Performance Of CdSe/Cds Based On Energy Transfer Regulation

Energy transfer is a dynamic process in which the excited energy is transferred from excited donor to the ground state receptor.According to the mechanism of energy transfer process,energy transfer can be divided into radiation energy transfer and non-radiation energy transfer.Radiation energy transfer results in the release of energy in the form of photons,that is,the energy released by the excited donor is absorbed by the receptor,causing the receptor to be excited,thereby causing the acceptor substance to emit light.Nonradiative energy transfer is the nonradiative energy transfer between receptor and donor,which must follow the total energy conservation of the system.Despite of the numerous types and complex mechanism of energy transfer,but the application of energy transfer as an effective experimental means can effectively control the fluorescence property of variety of fluorescent substances.In this paper,CdSe/CdS with good fluorescence properties were selected as the research object,gold/silver bimetallic nanoparticles and branched zinc phthalocyanine were used respectively as the exogenous fluorescence control substances,based on the mechanism of Metal Enhanced Fluorescence and Fluorescence Resonance Energy Transfer,the fluorescence properties of CdSe/CdS were systematically researched under the energy transfer regulation.(1)Adjusting the quantum dot fluorescence by gold and silver alloy nanoparticles.The noble metal nanoparticles have local surface plasmon resonance(LSPR)effect.Under a certain frequency light field,coupling effect occurs between the plasma on the metal surface and fluorescent molecules,that is,under the excitation wavelength,the fluorescent molecules will transfer their energy to the metal,which leads to the metal surface plasmon emission.In this process,the metal surface plasmon emission is resulted in not only by fluorescence molecules' own energy transfer,but also by the plasma coupled emission induced by excitation of light.The first step is to synthesize different sizes of gold and silver alloy nanoparticles,and the alloy nanoparticles are placed directly around the CdSe/CdS.It is found that the quenching of fluorescence of the CdSe/CdS appears,and the bigger the size of nanoparticles is,the more obvious the quenching is.Then,a layer of silica is assembled on the surface of the gold-silver alloy nanoparticles,and the treated alloy nanoparticles are placed around the CdSe/CdS to enhance the fluorescence of the CdSe/CdS.(2)In the first part,the effect of regulating the fluorescent of CdSe/CdS by inorganic nanoparticles is not good,and according to the report of many researchers,fluorescent molecules can also adjust the fluorescence of CdSe/CdS.Branched zinc phthalocyanine is a kind of good fluorescence,and with the application of the branched phthalocyanine zinc with dual emission band,the fluorescence of CdSe/CdS can also be regulated.In this study,we have found that the branched zinc phthalocyanine around the CdSe/CdS can stabilize the existence of CdSe/CdS,and then the fluorescence resonance energy transfer between CdSe/CdS and branched phthalocyanine zinc occurs,then the CdSe/CdS / branched phthalocyanine zinc hybrid materials with multi-band fluorescence emission are acquired.(3)With the CdSe/CdS / branched phthalocyanine zinc hybrid materials with multi-band fluorescence emission prepared in the last part,we make further efforts to study the behavior of branched zinc phthalocyanine in the solvent,and found that branched zinc phthalocyanine is very sensitive to water.When a small amount of water was introduced,the red emission of branched zinc phthalocyanine was found to disappear.Based on this phenomenon,water was introduced into the CdSe/CdS / branched zinc phthalocyanine nanocomposites and it promotes the fluorescence resonance energy transfer between CdSe/CdS and branched phthalocyanine zinc,reinforcing the fluorescence of CdSe/CdS,at the same time,due to the existence of CdSe/CdS,the red emission of branched zinc phthalocyanine was found to be retained.