| The semiconductor quantum dots (QDs) are zero dimension nanocrystal composing ofⅡ-ⅥandⅢ-Ⅴelements with the particle sizes ranging from 2nm to 10nm. Due to their strong quantum size effect,QDs exhibit unique and superior electronic, optics and surface function and show great research and application value in photoelectric conversion, semiconductor devices and biomarker areas. As a new fluorescent material, the QDs have wide excitation spectrum, narrow symmetrical emission spectrum, longer fluorescence life, better light stability and high photoluminescence yield compared with traditional organic fluorescencent dyes. QDs were mainly synthesized via orgnaic phase, microemulsion and aqueous synthesis, because of harsh reaction conditions, high costs of raw material and toxicity, the method of orgnaic phase and microemulsion synthesis were limited to practical application. QDs in aqueous synthesis have the good biological compitability and are directly used as labeling material. It has been mature for synthesis and research ofⅡ-ⅥCd-containing series QDs, but the toxity of heavy metals Cd limits their research and application in biomarkers field. In this thesis, highly fluorescent water-soluble InP/ZnS QDs were prepared via phase transfer and UV-irradiation processing, a series of ZnSe based luminescent QDs were also prepared. These QDs are low-toxic or non-toxic attributing to be as green luminescent ones leading to more broad prospects in biomarkers areas. The effects of preparation routes, structure and fluorescent property of QDs on the fingerprint developing on the surface of different objects were also systematically studied and discussed. The experimental results are given as follows:1,InP QDs were synthesized via solvothermal and chemical method, respectively. Then the water-soluble InP/ZnS QDs with different particle size of 3-4nm were synthesized by changing the synthesis temperature using toluene as solvent, DDA as coating agent and mercaptoacetic acid as modifier. The best emission wavelength of InP/ZnS QDs synthesized at different temperature are 438nm,508nm and 575nm respectively. The fingerprint details on the surface of smooth objects were clearly developed with water-soluble QDs solution synthesized at weaker alkaline conditions under irradiation of UV lights.2,The aqueous solutions of ZnxCd1-xSe QDs with smaller and homogeneous particle sizes were synthesized by using Se,Na2SO3 and Cd(NO)3·2H2O as precursor and thioglycollic acid (TGA) as modifier. The effects of refluxing time, initial pH value of the reaction and the molar ratio between Zn and Cd on the particle size and fluorescence intensity of ZnxCd1-xSe QDs were studied. Through XRD,HRTEM and fluorecence spectra, it is found that the content of Cd-doped ZnxCd1-xSe QDs with crystalline size of about 5nm increases, the best fluorescent emission wavelength were changed from 430nm to 585nm. The color of mimeograph fingerprint details on the surface of smooth objects is blue. The doped Zno.77Cdo.23Se QDs has the best result for developing fingerprint. The fingerprint details on the surface of smooth objects with different background colors were clearly developed with ZnxCd1-xSe QDs solution under UV irradiation, the effect of blood latent fingerprints is also well.3,The water-soluble fluorescent Mn2+:ZnSe QDs was synthesized by using Na2SeSO3 as Se precursor. Compared with mercaptoacetic acid and mercaptoacetic ethanol as the modifiers, Mn2+:ZnSe QDs synthesized with mercaptopropionic acid as modifier are most stable and strongest fluorescence intensity around 485nm. The XRD and HRTEM were also employed to characterize the sample. It is found that Mn2+:ZnSe QDs are small crystalline size and uniform dispersion. The fingerprint details on the surface of different smooth objects were clearly developed with Mn2+:ZnSe QDs. After UV- irradiation, fluorescent intensity of ZnSe/ZnS QDs was obvious enhanced, XRD characterization showed that the particle size was about 4.8nm, the color of fingerprint was purple or shallow blue. |
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