Characterisation of Nanoparticles Synthesized in the Microwave Plasma Discharge Process by Particle Mass Spectrometry and Transmission Electron Microscopy

The physical and chemical properties of nanoparticles frequently depend on their particle size distribution. Previous studies have shown that the microwave plasma (MWP) process yields non-agglomerated nanoparticles in the size range up to 30 nm (Vollath and Sickafus, 1992). The approximate size from bulk samples was determined by Transmission Electron Microscopy TEM. However the sampling and accurate picture analysis of these particles by TEM is very difficult due to their poor contrast and overlapping of particles. More recently Janzen et al. (2002) and Mätzing et al. (2003) reported the first full characterisation of various metaloxide nanoparticles from the MWP by particle mass spectrometer (PMS). These size distributions show modal values of 4 – 5 nm (ZnO, Fe2O3, SiO2) and narrow geometric standard deviations. The comparison of PMSand TEM-derived sizing information shows that the PMS is a reliable and efficient tool for the investigation of the MWP process. Here we report our results concerning the influence of precursor concentration and microwave power on the size distribution of iron oxide and silica nanoparticles produced by the MWP.