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| Titel |
Absorption Ångström coefficient, brown carbon, and aerosols: basic concepts, bulk matter, and spherical particles |
| VerfasserIn |
H. Moosmüller, R. K. Chakrabarty, K. M. Ehlers, W. P. Arnott |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 3 ; Nr. 11, no. 3 (2011-02-14), S.1217-1225 |
| Datensatznummer |
250009303
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| Publikation (Nr.) |
 copernicus.org/acp-11-1217-2011.pdf |
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| Zusammenfassung |
| The concept of wavelength-dependent absorption Ångström coefficients
(AACs) is discussed and clarified for both single and two-wavelengths AACs and
guidance for their implementation with noisy absorption spectra is provided.
This discussion is followed by application of the concept to models for
brown carbon bulk absorption spectra including the damped simple harmonic
oscillator model, its Lorentzian approximation, and the band-gap model with
and without Urbach tail. We show that the band-gap model with Urbach tail
always has an unphysical discontinuity in the first derivative of the AAC at the
band-gap – Urbach-tail matching wavelength. Complex refractive indices
obtained from the bulk damped simple harmonic oscillator model are used to
calculate absorption spectra for spherical particles, followed by a
discussion of their features. For bulk material and small particles, this
model predicts a monotonic decrease of the AAC with wavelength well above the
resonance wavelength; the model predicts a monotonic increase for large
particles. |
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