【作者】 彭凌霄；

【导师】 刘祖黎；

【作者基本信息】 华中科技大学 ， 材料物理与化学， 2006， 硕士

【摘要】 金纳米团簇由于其理想的光性能和电性能目前成为了研究领域的热点之一。研究表明,当金颗粒尺寸逐渐减小到和电子的费米波长相当时(通常<1.5nm),由于量子尺寸效应,会呈现出和半导体类似的特征,产生分立能级,并会受激发射出荧光。相对于传统的荧光标记物而言,金纳米团簇具有许多优势。荧光染料分子容易产生光熄灭;半导体纳米颗粒作为一种新的荧光标记物,制备条件苛刻,需高温绝氧,并且合成先驱物有高毒性;而金纳米团簇在非常温和的条件下就能合成,并且发光颜色随团簇尺寸可调,作为一种潜在的荧光标记物,有望广泛的用于光成像、生物标记、LED光电显示等领域中。目前合成金纳米团簇主要采用硫醇配体修饰金颗粒的Schiffrin法。在这个方法中,两个关键点就是金纳米颗粒的尺寸控制和配体选择。本文仍采用Schiffrin法,在反相微乳液中,通过采用含两个巯基(SH)的硫醇做配体,得到了金颗粒交错互连成球体状的奇异的金纳米团簇结构,并发现该产物表现出了优越的荧光性能。据我们所知,这是第一次用传统的Schiffrin法制备出了发蓝色荧光的金纳米团簇,并且发光量子效率较以往报道的结果提高了将近三个数量级,达到了15%左右。我们对产物进行了详细表征,并通过和以往报道的结果对比,解释了我们实验中观察到的优异荧光性能的来源,并对如何选择合适的硫醇配体达到此效果提出了建议。更多还原

【Abstract】 Gold nanoclusters have received much attention owing to their novel optical and electronic properties. Researches point out that Au particles, when their sizes decrease to comparable to the Fermi wavelength of an electron (usually <1.5nm), the quantum effect becomes apparent and the gold nanoparticles start to exhibit semiconductor electronic characteristics. The band gap begins to evolve, and luminescence will be observed under excitation.Compared to traditional fluorescent labels, Au nanoclusters have lots of advantages. Dye molecules are limited by photobleaching. Semiconductor nanocrystals, which have recently been introduced as labels, require toxic precursors and should be prepared under inert atmosphere at high temperature. On the contrary, the Au nanoclusters can be easily synthesized under mild conditions and show size-dependent emission. As an appealing optical label, Au nanoclusters have great potential to be used in imaging, biological labeling and LED related fields.To date, Au nanoclusters have been usually synthesized using Schiffrin method. Two key issues in this method are properly controlling the size of the Au particle and on the capping or protecting ligands bonded to the particle surface. In our study, also using Schiffrin method, we synthesized Au nanoclusters which were modified by a special dithiol ligand in reverse microemulsion, and astonished to observed novel fluorescent property. To the best of our knowledge, this is the first time the blue luminescence is observed from Au nanoclusters prepared by Schiffrin method, and the quantum efficiency is greatly enhanced to about 15%, which is more than 100-fold improvement over the best result reported.According to the detailed measurement results of our sample and compared to the reported results, we give explanations to the novel luminescence observed in our experiment. And we also give some suggestions on how to choose the appropriate ligand.更多还原