Self-organization of C60 nanoparticles in carbon disulfide solution
Self-organization of C60 nanoparticles in carbon disulfide solution
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DOI：
10.1021/jp0340717
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发表时间：
2003-06-26
影响因子：
3.3
通讯作者：
Patnaik, A
中科院分区：
文献类型：
--
作者：
Bokare, AD;Patnaik, A
C-60聚集在纯CS2溶剂中的报道使用正电子素（Ps）作为基本探针，其映射微环境的局部电子密度的变化。Ps原子与周围环境的特定相互作用戏剧性地揭示了在该溶剂中稳定聚集体形成的起始浓度为0.06 g/dm（3）。在0.06-0.36 g/dm（3）的窄浓度范围内，观察到在胶体范围（类似于90 -125 nm）内自发形成稳定的聚集体，超过该浓度，团簇破裂。聚集体性质随尺寸的变化（与τ（3）[PS寿命]和/或λ（3）[Ps湮灭率，1/τ（3）]成比例）是值得注意的。Ps湮灭特性与透射电子显微镜和紫外-可见吸收光谱的确证表明，溶液相C-60结构是一个球形分形聚集体的分形维数为1.9，生长模式遵循扩散限制的簇聚集机制。在超过0.36 g/dm（3）的较高浓度下，注意到熵驱动相变，导致形成不规则但定向的结晶组分。
C-60 aggregation in neat CS2 solvent is reported using positronium (Ps) as a fundamental probe, which maps changes in the local electron density of the microenvironment. Specific interactions of the Ps atom with the surrounding dramatically reveal the onset concentration for stable aggregate formation in this solvent to be 0.06 g/dm(3). Spontaneous formation of stable aggregates in the colloidal range (similar to90-125 nm) was observed over a narrow concentration range of 0.06-0.36 g/dm(3), beyond which the clusters broke. Variation of aggregate properties with size (proportional to tau(3) [PS lifetime] and/or lambda(3) [Ps annihilation rate, 1/tau(3)]) are noteworthy. Ps annihilation characteristics in corroboration with transmission electron microscopy and UV-vis absorption spectroscopy demonstrate the solution phase C-60 structure to be a spherical fractal aggregate with fractal dimension 1.9 and that the growth mode follows a diffusion-limited cluster aggregation mechanism. At a higher concentration beyond 0.36 g/dm(3), an entropy driven phase change was noticed leading to formation of irregular, but oriented crystalline components.