Two aspects of particle sizing in the sub 100 nm size range with a Scanning Mobility Particle Sizer (SMPS) are discussed in this paper. Fast sizing on the one hand is crucial to obtain reliable data in case of changing aerosols. Measurement data is presented that demonstrates the ability to measure complete size distributions with high accuracy at scan-times down to 5 seconds. On the other hand data obtained with a 1 nm SMPS-system optimized for the smallest sizes below 2.5 nm will be discussed.
