Generation of Calibration Aerosols

Calibration of the instruments to measure the size distribution and chemical composition requires methods of generating aerosols of well-defined sizes and known composition. Generating aerosols of known 

A monodisperse aerosol is one with a narrow size distribution, which, for log-normal-distributed particles, usually means a geometric standard deviation of about 1.2 or smaller. Monodisperse particles are expected to have simple shapes and uniform composition with respect to size. A polydisperse aerosol, on the other hand, is one containing a wide range of particle sizes, but which may otherwise be homogeneous in terms of the basic physical and chemical properties that are not related to size. The term heterodisperse is also used occasionally this describes aerosols varying widely in physical and chemical characteristics, as well as size. 

As discussed in detail by Raabe (1976), an investigator s use of the terms monodisperse and polydisperse aerosols may depend on the particular properties of importance in the study thus an aerosol may consist of particles of the same size, that is, be monodisperse with respect to size, but may vary in settling speed due to variations in density, that is, be polydisperse with respect to settling speed. 

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