Study of Quasi-Fractal Many-Particle-Systems and Percolation Networks by Zero-Loss Spectroscopic Imaging, Electron Energy-Loss Spectroscopy and Digital Image Analysis

Abstract

Abstract. Submicron colloidal Ag particles and nano-sized filaments forming a statistical percolation network during "in situ" development of double structure tabular microcrystals of AgBr(I) emulsions have been studied by electron energy-loss spectroscopy and zero-loss electron spectroscopic imaging (EELS/ ZLESI). Image analysis has shown that random quasi-fractal clusters were formed in the colloid. ZLESI has been applied to characterise the morphology and defect structure of aggregated particles and filaments. Their energy-loss spectra revealed plasmon excitations and interband 4d electron transitions between 4-32 eV energy-loss. To study the cluster structure and its relation to the physical properties, fractal analysis including estimations of cluster fractal dimensions and of density autocorrelation functions has been performed. Mechanisms of fractal aggregation based on known models of diffusion limited aggregation, cluster-cluster aggregation and percolation are discussed.

Use of Plasmon Spectroscopy to Evaluate the Mechanical Properties of Materials at the Nanoscale

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