| The synthesis and analytical application of semiconductor nanomaterials gained increasing attentions of scientists in the past two decades and the quantum dots have become the most extensively investigated one among them. Compared with the traditional organic fluorescent dye, The quantum dots exhibit remarkably important advantages, including broad excitation spectrum, the tunable and narrow emission spectrum, large stokes displacement and high photobleaching threshold and excellent photostability.Three chapters are included in this thesis. The first chapter is review. In this chapter the basic characters and photoluminescence properties of quantum dots, surface modification of quantum dots as well as the applications of quantum dots as fluorescent probe and their progress are reviewed. The second and third one are research reports. In the research part, thioglycolic acid capped and water soluble CdTe quantum dots were prepared; Fluorescent properties of the quantum dots were studied; Interaction between CdTe quantum dots and CTAB was discussed based on the electrostatic interaction; A analytic method for Hg (II) in water samples was proposed with the quantum dots as fluorescent probe based on the linearity relativity between the concentration of quantum dots and its fluorescence quenching ratio.The research report contains two subunits:1.The fluorescence properties of CdTe quantum dots and its interaction with CTABThioglycolic acid (TGA) capped CdTe quantum dots were prepared in aqueous solution and its interaction with CTAB was studied. The synthesized CdTe quantum dots were characterized by transmission electron microscopy, spectrofluorometry and ultraviolet-visible spectrometry respectively. The particle size and fluorescence properties of CdTe quantum dots influencing by reaction time and the stability of CdTe quantum dots were studied. The results showed that the synthesized quantum dots held excellent optical properties, good distributions and considerable stabilities. The needed quantum dots could be prepared by controlling reaction time. The fluorescence intensity of quantum dots was reduced after adding CTAB. Fluorescence quenching ratio of quantum dots exhibited different trends of when the CTAB concentration changed from 1.0×10-6 mol/L to 1.0×10-4 mol/L. The maximal emission wavelength of quantum dots also changed with the fluorescence intensity altered. Based on the experimental results. The interaction between quantum dots and CTAB was discussed elementaryly and considered that above mechanism was the electrostatic interaction.2. Surface Modified CdTe Quantum Dots as Luminescence Probes for Detection of Trace Mercury Thioglycolic acid (TGA) capped CdTe quantum dots were prepared in aqueous solution. The synthesized CdTe quantum dots were characterized by transmission electron microscopy, spectrofluorometry and ultraviolet-visible spectrometry respectively. Based on the quenching of fluorescence signals of functionalized CdTe quantum dots at maximal emission wavelength in the presence of Hg (II), the prepared CdTe quantum dots were evaluated as fluorescence probe for Hg (II) detection. Various factors affecting the fluorescence detection for Hg (II) with CdTe quantum dots were investigated including buffer system, pH of buffer, reacting time and concentration of quantum dots. Under optimum experiment conditions, a good linear relationship between the logarithm of fluorescence intensity ratio of system and concentration of mercury ions was observed, the linear rang was from 8×10-9 to 1.5×10-7mol/L, with the detection limit of 2×10-9mol/L. To 3.0×10-8 mol/L standard, the relative standard deviation was 3.5% for eleven times parallel measurements. |
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