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Start of funding 01.07.2005

New Analytical Tools for Characterization of Precursors of Cloud Condensation Nuclei

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We intend to develop, optimize and use new analytic tools to characterize the structure and growth mechanisms of precursors for cloud condensation nuclei (CCN, ionic H2SO4/H2O aerosol particles). For this purpose, we develop an efficient H2SO4/H2O particle source and analyze their composition, structure, and photochemistry by modern mass spectrometric and laser spectroscopic techniques as well as quantum chemical calculations. The results provide new insight into the growth mechanism of atmospheric aerosol particles at the molecular level and the basis for the direct spectrosopic observation of CCN precursors in the atmosphere. This will improve our understanding of the generation of aerosol and CCN particles in our atmosphere.

Final report:
In this joint project, we have developed, optimized, and applied a new cluster and aerosol particle ion source for cloud condensation nuclei (CCN), in particular for ionic H2O/H2SO4 and H2O/H2CO3 clusters, in order to investigate their composition, structure, and photochemistry by modern IR laser spectroscopic, mass spectrometric, and quantum chemical tools. Initial results for the H2O/H2CO3 system have already been published in a high impact journal [1]. The results provide new insight into the growth mechanism of these cluster particles at the molecular level and the basis for the direct spectroscopic observation of CCN precursors in the atmosphere. Eventually, this will improve our understanding of the generation of aerosol and CCN particles in our atmosphere.

[1] Structure and IR spectrum of protonated carbonic acid, H.-S. Andrei, S.A. Nizkorodov, O. Dopfer, Angew. Chem., in press (2007), DOI: 10.1002/ange.200700750.