Radiation Response Characteristics And Mechanism Of Functionalized Quantum Dots And Fluorescent Molecules

Nuclear technology has become more and more widely used in energy,medicine,industry and other fields,which has produced important economic effects.It has become an important research topic that how to effectively detect and effectively evaluate the effects of radiation with important needs and application background.Based on the actual demand of radiation dose detection,this paper conducts research work on radiation sensitive materials,explores the response law and mechanism of fluorescent molecules and functionalized quantum dots to gamma radiation.It may provide basis for the development of a new type of radiation detector.The main research contents and results of this paper are as follows:?1?In this paper,the fluorescence properties of 2,6 bis?2-benzimidazolyl?pyridine fluorescent materials on different conditions?different solvents,different radiation doses and different concentrations?under gamma ray irradiation were studied in detail.Fluorescent molecules in methylene chloride and higher concentrations of chloroform solvent,the fluorescence intensity decreases with increasing irradiation dose.In lower concentrations of chloroform solvent,the fluorescence intensity increases with increasing irradiation dose.Fluorescent molecules in dichloromethane and chloroform solvent concentrations of 8×10^-6 and 8×10^-7 mol/L radiation response gradients are best,in the 0-100 Gy gamma radiation dose range,linear fit correlation The coefficients are 0.990 and 0.895,which proves that this molecule has an opportunity to be used as a convenient and fast gamma radiation dose detecting material.Based on the test results,the mechanism of the above phenomenon was analyzed and discussed.?2?Three different surface-modified CdTe and CdSe quantum dots of thiol-compounds?mercaptopropionic acid and mercaptoethylamine?were hydrothermally synthesized,which were MPA-CdTe,MPA-CdSe and Cys-CdTe quantum dots,respectively.The microstructure and luminescence properties were tested and characterized by HRTEM,XRD,FTIR,XPS,PL and UV-vis.The test results show that their particle sizes are 3.4,4.1 and 3.9 nm,respectively.?3?The radiation response of gamma-rays to functionalized CdTe and CdSe quantum dots with different thiol-compounds was investigated.The change of fluorescence intensity of quantum dots under different irradiation doses was studied.The effect of quantum dot particle size and oxygen on the phenomenon of radiation-induced fluorescence enhancement was investigated.It was found that the quantum dot fluorescence intensity increased significantly with increasing dose within a certain radiation dose range.The effects of different surface modification,structural composition,and quantum dot size on the enhancement of the radiation-induced fluorescence are not obvious,and the presence of oxygen accelerates the process.Based on the quantum dot response to radiation dose,it can be used to enhance quantum dot luminescence performance,and can be used to develop new radiation dosimeters.?4?The mechanism of?-radiation induced QDs photoluminescence enhancement is also discussed.The luminescence properties and structure of quantum dots before and after irradiation were characterized and analyzed by HRTEM,XRD,FT-IR and XPS.The phenomenon of radiation luminescence enhancement of water-soluble quantum dots is mainly attributed to the radiochemical reaction initiated by gamma radiation in aqueous solution.The resulting active species act on the surface of the quantum dots to produce S^2-and Cd²⁺,which form a CdS shell on the surface of the quantum dots,reducing surface traps and defects of CdTe and CdSe quantum dots.At the same time,the band gap of CdS is larger than the band gap of CdTe and CdSe.Therefore,the formed CdS shell layer significantly improves the fluorescence efficiency of the water-soluble quantum dots.