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Study on Preparation and luminescence properties of alkali metal and rare earth fluoride nanocrystals by near infrared fluorescence labeling

Author: WangXue
Tutor: QiuJianBei
School: Kunming University of Science and Technology
Course: Materials Science
Keywords: Rare earth fluoride of an alkali metal up conversion luminescence downconversion luminescence nanocrystals controlled synthesis
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Type: Master's thesis
Year: 2013
Downloads: 34
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Abstract


Due to the demand for biomedical research and clinical treatment, semiconductor nanoparticles, fluorescent proteins, fluorescent organic molecules as a fluorescent probe optical imaging technology has been more and more widely used in vivo imaging studies. But organic molecules due to the small Stokes shift, poor light stability, prone to optical bleaching; main group III-V semiconductor quantum dots because of its heavy metal potential biological toxicity but also occurs when the illumination light flicker that limits they are widely applied in the field of biological markers. In recent years, near-infrared light excitation rare earth ion doping on the upconversion of nano probe to avoid the above problems, but in the low efficiency of Upconversion luminescence process to some extent limits the imaging depth and range of application of this kind of probe.This thesis focuses on the lack of existing near-infrared excitation upconversion type rare earth mark Nanoparticles as Fluorescence Probes, Proposed by Nd3+-Yb3+co-doped,used of energy transfer to achieve efficient of near-infrared excitation-near-infrared emission of the down-conversion fluorescent nanocrystals. In addition,we droped Er3+to obtain efficient of up and down-conversion fluorescent nanocrystals on this basis. The main results obtained are as follows:(1) Oleic acid as surfactant were prepared relatively pure crystalline phase of Nd3+doped nano a-NaYF4/β-NaYF4/β-NaGdF4by hydrothermal method, and then characterization the structure and fluorescent properties of nanocrystals. We observed in the above-described samples of Nd3+880nm,1064nm,1350nm intense near-infrared emission in the near-infrared light of800nm excitation. We observed in the above-described samples of Nd3+with emissions from the excited4F3/2state tI9/2(890nm),4I11/2(1060nm) and4I13/2(1340nm) manifolds under a laser pump at808nm, which showed a good excitation and emission luminescence in the NIR region.(2) We observed near-infrared down conversion luminescence of Yb3+in Nd3+-Yb3+co-doped nano a-NaYF4/β-NaYF4/β-NaGdF4,Compared different crystal structure of the fluorescent phenomenon, discussed the relationship between the downconversion luminescence intensity and doping concentration and the structure of the phase type under a laser pump at808nm.(3)Nd3+-Yb3+-Er3+doped a-NaYF4/β-NaYF4/β-NaGdF4nanocrystals with up conversion and down conversion luminescence properties at the same time. The study found that different crystal structure of a-NaYF4/β-NaYF4/β-NaGdF4up and down conversion luminescence there is a difference, especially up conversion luminescence when excited by light in the980nm pump that different crystal structure of NaY(Gd)F4, which green and red luminous intensity, fluorescence mechanism also has a significant difference. Our preliminary analysis of the difference that may be the cause of the experimental results show in the case of the same amount of rare earth doped NaY(Gd)F4, which have strong down-converted light-emitting and more prominent of monochromatic on the convert. The material used in biological fluorescence depending on the crystal structure to achieve multi-colored markers. We have a preliminary analysis of the difference may be the cause of. The experimental results show that in the case of the same amount of rare earth doped NaY(Gd)F4of the down-converted light emitting strong up conversion monochromatic more prominent.

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