Open AccessInfrared complex refractive indices of supercooled liquid HNO 3 /H 2 O aerosols
Author(s) -
Norman M. L.,
Qian J.,
Miller R. E.,
Worsnop D. R.
Publication year - 1999
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999jd900902
Subject(s) - amorphous solid , refractive index , extinction (optical mineralogy) , aerosol , materials science , mie scattering , supercooling , analytical chemistry (journal) , infrared , scattering , optics , light scattering , mineralogy , chemistry , meteorology , physics , optoelectronics , organic chemistry
Complex refractive indices have been retrieved for the first time directly from the Fourier transform infrared extinction spectra of supercooled liquid HNO 3 /H 2 O aerosols at 220 K. Aerosol compositions were determined by simultaneously monitoring equilibrium HNO 3 and H 2 O vapor pressures with a tunable diode laser. The new optical constants are compared with previous results from room temperature bulk solutions and <160 K amorphous solid thin films, and the differences are explained primarily in terms of the temperature‐dependent dissociation of molecular HNO 3 into its constituent ions. Mie scattering analysis of aerosol extinction spectra suggests that using either the room temperature liquid or the amorphous solid refractive indices may result in inaccurate particle size determination. These new data sets are directly applicable to the characterization of polar stratospheric clouds through spectroscopic remote sensing.