Fractal analysis of wood combustion aggregates by contact mode atomic force microscopy

Atomic force microscopy (AFM) is a powerful tool for the characterization of nanoparticles allowing to obtain fundamental parameters of morphology such as the size of individual particles, the number of particles per aggregate, the size distribution and finally the AFM allows one to determine the volume. All these parameters are accessible for the native aspect of the particles while AFM works under ambient temperature and pressure. We present here the analysis of wood combustion particles and their morphological parameters. Using our results for the 3D values, we were able to calculate the fractal dimension (Df) of the aggregates. As the Df is characteristic to the aggregation regime that particles undergo, we determined that wood particle aggregates follow a diffusion limited aggregation regime (Df=1.95). In parallel, in-situ analysis of the hydration effect has been studied in water at pH 7 and shows that the morphology is significantly influenced by the hydration. The composition observed by analytical electron microscopy (AEM) and atomic emission spectrometry (AES) enabled us to correlate the in-situ measurements by AFM with the hydration behavior of these particles and the fractal dimension.