Physicochemical properties of gold nanoparticle crystals

在本项目中，我们针对人工设计的量子效应晶体，研究了基于表面修饰的金纳米粒子的自组装制备纳米量子晶体，不同于所谓的颗粒晶体形成或纳米粒子密集堆积的制备。主要研究结果如下：1)采用胶体化学技术在水中大规模合成了金纳米粒子。以硫代琥珀酸(MSA)为表面修饰剂，建立了0.1~1g的规模。2)高产率合成了金纳米晶体。基于DLVO理论，发展了金纳米晶体在空气/水界面上的自由结晶。3)金纳米晶体的光学吸收光谱。我们观察到金纳米晶体多晶薄膜中的特征光谱，这与孤立粒子或随机堆积粉末样品的溶液光谱不同。4)金纳米晶的STM观察表明，金纳米晶表面被致密的单分子膜MSA覆盖。5)金纳米晶的结构表征。用X射线衍射法和TED法对金纳米晶进行了结构表征。6)表面修饰分子的化学修饰。用吡啶羧酸对表面MSA分子进行了酯化反应，得到了金纳米粒的单层膜。

In due course of this project, we have studied the preparation of a nano-quantum crystal based upon self-assembling of surface modified gold nanoparticles, different from so-called particle crystal formation or the preparation of dense packing of nanoparticles, aiming the artificially designed quantum effect crystals. The results are classified as follows.1) Large scale synthesis of gold nanoparticles in water by colloidal chemistry technique.The scale of 0.1〜1g quantity was established by using mercaptosuccinic acid (MSA) as a surface modifier.2) High yield synthesis of gold nanoparticle crystals.Free standing crystallization at an air/water interface was developed based on DLVO theory.3) Optical absorption spectrum of nanoparticle crystals.We have observed a characteristic optical spectra in polycrystalline film of gold nanoparticle crystals, which differed from solution spectra typical of isolated particles or random packing of powdered samples. The broad surface plasmon band located at 520 nm observed in isolated particles was sharpened and shifted to lower energy side suggesting strong interparticle interaction likewise of exciton or J-band of cyanine dyes.4) STM observation of gold nanoparticle crystals.STM technique was applied to the particle crystal revealing that the surface of gold nanoparticles are densely covered with monolayer MSA.5) Structural evaluation of gold nanoparticle crystals.XRD and TED method are applied to a good crystal of gold nanoparticles revealing hcp densely packed structure.6) Chemical modification of surface modifier molecules.Esterification reaction was taken place against surface MSA molecules using pyridine carboxylic acid giving monolayer film of gold nanoparticles.