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| Titel |
Electrodynamic balance measurements of thermodynamic, kinetic, and optical aerosol properties inaccessible to bulk methods |
| VerfasserIn |
S. S. Steimer, U. K. Krieger, Y.-F. Te, D. M. Lienhard, A. J. Huisman, B. P. Luo, M. Ammann, T. Peter |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 6 ; Nr. 8, no. 6 (2015-06-08), S.2397-2408 |
| Datensatznummer |
250116428
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| Publikation (Nr.) |
 copernicus.org/amt-8-2397-2015.pdf |
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| Zusammenfassung |
| Measurements of a single, levitated particle in an electrodynamic
balance are an established tool for deriving thermodynamic and
material data such as density, refractive index and activities of
components of an aqueous solution under supersaturated conditions,
where bulk measurements are not possible. The retrieval relies on
combining mass-to-charge data and size data from light scattering.
Here, we use a combination of low- and high-resolution Mie resonance
spectroscopy to obtain radius data, enabling an accurate size
determination not only when the particle is in equilibrium, but also
when it is out of equilibrium due to kinetic limitation of mass
transport. With the data measured under non-equilibrium conditions, it
is possible to retrieve the water diffusivity. A challenge is that the
radius retrieval by comparing measured light scattering with Mie
theory requires the knowledge of refractive index as a function of
concentration. Here, we show an iterative retrieval of refractive
index and size for compounds for which data cannot be obtained in the
bulk either due to lack of sufficient amounts of sample or limited
solubility. We demonstrate the measurement strategy and the retrieval
of water activity, density, refractive index and water diffusivity for
aqueous shikimic acid. Water diffusivity in concentrated shikimic acid
decreases by 6 orders of magnitude at 250 K compared to that
at room temperature. |
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