jp051942z_si_002.txt (12.09 kB)
Mid-infrared Extinction Spectra and Optical Constants of Supercooled Water Droplets
dataset
posted on 2005-08-18, 00:00 authored by Robert Wagner, Stefan Benz, Ottmar Möhler, Harald Saathoff, Martin Schnaiter, Ulrich SchurathComplex refractive indices of supercooled liquid water have been retrieved at 269, 258, 252, and 238 K in
the 4500−1100 cm-1 wavenumber regime from series of infrared extinction spectra of micron-sized water
droplets. The spectra collection was recorded during expansion experiments in the large coolable aerosol
chamber AIDA of Forschungszentrum Karlsruhe. A Mie inversion technique was applied to derive the low-temperature refractive index data sets by iteratively adjusting the room-temperature optical constants of liquid
water until obtaining the best agreement between measured and calculated infrared spectra of the supercooled
water droplets. The new optical constants, revealing significant temperature-induced spectral variations in
comparison with the room-temperature refractive indices, proved to be in good agreement with data sets
obtained in a recent study. A detailed analysis was performed to elaborate potential inaccuracies in the retrieval
results when deriving optical constants from particle extinction spectra using an iterative procedure.
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Mie inversion techniqueOptical Constantsconstantsupercooled water dropletsiterative procedureextinction spectraindex data setsspectra collectionSupercooled Water Droplets ComplexForschungszentrum Karlsruheexpansion experiments238 Kparticle extinction spectradata setsretrieval resultsindiceswavenumber regimecoolable aerosol chamber AIDA