Berlin 2001 – wissenschaftliches Programm

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A: Atomphysik

A 17: Posters Friday (Spectroscopy)

A 17.57: Poster

Freitag, 6. April 2001, 12:30–15:00, AT3

On-line laser mass spectrometry: A novel method for determination of optical parameters of aerosols — •Achim Trimborn, Klaus-Peter Hinz, and Bernhard Spengler — Schubertstr. 60, Haus 16, D-35392 Giessen

Atmospheric aerosols are known to influence earth climate by two major mechanisms, absorption and scattering of solar radiation on the one hand and cloud formation by condensation of atmospheric water on the other hand. For a better understanding of these atmospheric processes an exact characterization of physico-chemical parameters (particle number, chemical composition, refractive index, etc.) is mandatory.

The bipolar on-line laser mass spectrometer LAMPAS 2 provides for a simultaneous determination of the major properties of single aerosol particles. Mass spectra of positive and negative ions are recorded, as well as the aerodynamic diameters of individual particles.

A powerful fuzzy clustering algorithm is used to reduce the large number of single-particle mass spectra to a small number of ”mean” spectra patterns, each representing a certain class of particles. These spectra patterns are used to synthesize atmospheric aerosol particles in the laboratory and to determine additional aerosol properties (e.g. refractive index) in subsequent experiments.

The synthesis of atmospheric particles in the laboratory and the determination of optical parameters will be described. Relevance of the results for a better understanding of atmospheric processes will be discussed.