This title appears in the Scientific Report : 2003 

A quantitative test of infrared optical constants for supercooled sulphuric and nitric acid droplet aerosols
Wagner, R.
Mangold, A. / Möhler, O. / Saathoff, H. / Schnaiter, M. / Schurath, U.
Stratosphäre; ICG-I
Atmospheric chemistry and physics, 3 (2003) S. 1147 - 1164
Katlenburg-Lindau EGU 2003
1147 - 1164
Journal Article
Chemie und Dynamik der Geo-Biosphäre
Atmospheric Chemistry and Physics 3
J
OpenAccess
Please use the identifier: http://hdl.handle.net/2128/731 in citations.
In situ Fourier transform infrared (FTIR) extinction spectra of supercooled H2SO4/ H2O and HNO3/ H2O solution droplets were recorded in the large coolable aerosol chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere) of Forschungszentrum Karlsruhe for a range of aerosol compositions and at temperatures extending down to 192 K. The measured spectra were quantitatively analysed in terms of aerosol composition and mass concentration by using Mie theory in combination with published refractive index data as input parameters. Simultaneously, total sulphuric acid and nitric acid mass concentrations from filter analysis and total water concentrations measured with the Lyman-alpha hygrometer of Forschungszentrum Julich were used to calculate the aerosol composition at thermodynamic equilibrium inside the aerosol chamber. By comparing these measured aerosol parameters with those retrieved from the analysis of the FTIR spectra, the accuracy of the literature data sets of refractive indices could be assessed. In summary, four data sets were tested in the H2SO4/ H2O system as well as two data sets in the HNO3/ H2O system, partly revealing significant discrepancies in the retrieved aerosol properties. Potential explanations for these differences are discussed in this paper.