Using Positronium (Ps) atom as a fundamental probe that maps changes in the local electron density of the microenvironment and high resolution transmission electron microscopy, aggregation in neat solvent is reported over a concentration range Spontaneous formation of stable spherical aggregates in the colloidal range (∼90–125 nm) was observed over a critical concentration range of beyond which the clusters broke. Specific interactions of the Ps atom with the surrounding revealed the onset concentration for stable aggregate formation in this solvent to be The solution phase structure in the critical concentration range was analyzed to be a spherical fractal aggregate with a fractal dimension of 1.9 and the growth mode followed a diffusion limited cluster aggregation mechanism. At concentrations beyond an entropy driven phase change was noticed leading to the formation of irregular, but oriented crystalline components. A microscopic diffusion model was applied to calculate the o-Ps lifetime density function and diffusion coefficients of o-Ps and the aggregates in the solution. With randomly distributed fractal clusters, the o-Ps density function resulted in a good agreement between the calculated and the experimental o-Ps lifetimes, revealing the diffusion coefficients of fractal cluster and the o-Ps to be and respectively.
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Research Article| August 08 2003
Microscopic diffusion model applied to fullerene fractals in carbon disulphide solution
Alok D. Bokare;
Alok D. Bokare, Archita Patnaik; Microscopic diffusion model applied to fullerene fractals in carbon disulphide solution. J. Chem. Phys. 22 August 2003; 119 (8): 4529–4538. https://doi.org/10.1063/1.1594177
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