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The determination of particle size detection efficiency of condensation nucleus counters by means of polydisperse aerosols produced from soluble salt solutions and the problem of particle shattering upon chrystallization

: Holländer, W.; Schumann, G.


Atmospheric environment 13 (1979), Nr.9, S.1319-1327
ISSN: 0004-6981
ISSN: 1352-2310
Fraunhofer IUCT ( IME) ()

Experiments with an Environment/One condensation nuclei counter (CNC) and a series of 5 alkali halide aerosols produced by an atomizer showed that there was no change in fragmentation behavior for the different salts and solution concentrations so that the nuclei spectra could be calculated from the primary droplet spectrum. In a theoretical section the influence of humidification on particle size spectrum was calculated and confirmed by experiments: detectability of nuclei increases with hygroscopicity. This can be explained, however, only if the supersaturation is of very short duration so that the size advantage of the droplets compared to the nuclei is sufficient. The particle size detection probability for the CNC was calculated by inversion of the corresponding Fredholm's integral equation. It was thus possible to fit a series of 5 measurements with alkali halide aerosols by a single detection probability. The results are compared with previous experiments of different authors; they show essentially the same behavior.