Optical measurements of the temporal behaviour of spray and aerosols

Aerosols and sprays play an important role in technological and biological processes like internal combustion engines, environmental pollution, applications of pesticides and atmospheric processes. For the optimization of droplet size in such processes it is essential to know the temporal behaviour of parameters of the droplets, like size, evaporation rate, temperature, surface tension and hydrodynamic behaviour. Holographic investigations of droplets and sprays are extremely expensive and will only bring little information. But optical and spectroscopic measurements on spatially fixed droplets and sprays will bring essential information on heat and material transport through the surface of small droplets. We will report on a new electromagnetic trap which is able to stabilize single particles as well as particle clouds with droplet diameters up to 50 µm. The trap offers the advantages of carry out optical measurements within a very wide space angle. Measurements on temperature, evaporation rates, concentrations and densities as well as mass transport in droplets by using optical scattering and spontaneous Raman Scattering will be reported.