| Lecturer Profile |
Prof Fabrice R.A. ONOFRI is Director of Research at CNRS, laboratory IUSTI, Marseille. His research activity is focused on the development of electromagnetic tools, for the direct and inverse characterization of particle and particle systems, based on the analysis of their light scattering properties. He has nearly 145 journal and conference papers, 2 monographs, 4 book chapters and 2 patents. |
| Lecture Abstract |
Nanoparticles have generated considerable interest due to their unequalled specific surface, chemical activity, mechanical strength, or their electrical and optical properties for instance. Issues related to their possible health and safety hazards when released in the environment have also raised concerns. The characterization, the remote control and monitoring of these particles is thus of importance. To do this, our approach is essentially based on the light extinction spectrometry and small angle scattering techniques. While the principles of the later are known for decades, several issues must be addressed to implement these techniques: particle morphology (acicular, buckyball, fractal, …), light scattering models, inverse techniques, experimental setups and validation techniques, etc. All these aspects will be illustrated when characterizing aerosols, colloid suspensions, dusty and fusion plasmas. The second part of this talk will be focused on larger particles and, more particularly, the characterization of droplets and bubbles in two-phase and multiphase flows. The latter are at the heart of a tremendous number of phenomena and processes: car and rocket engines, driers units, fluidized beds, liquid-liquid extraction colons, etc. The first group of techniques that we are developing: rainbow and critical diffractometry, allows to obtain the size distribution and composition of single or clouds of droplets and bubbles. The bubbles and droplets being not necessarily spherical and homogeneous, a special consideration is put of the development of ad hoc light scattering models. More recently, we also start to work on near field-techniques, and more particularly the on-line digital holography which brings additional information on the 3D position and dynamics of the dispersed phase. The stress will be put solutions to account for some astigmatism in the system, as well as the improvement particle on-axis position through the analysis of the photonic jet. |
