Spectra of the real and imaginary parts of the refractive index m = n′ − in″ from 2.5 μm to 40 μm of ammonium sulfate, Sahara dust (as collected at Barbados), volcanic dust (pumice), and dust from a coal-fired power plant are presented. With a peak absorption index n″ = 1.0 at 10 μm Sahara dust turns out to be the strongest absorber in the atmospheric window. The dispersion of n′ is also very pronounced near 9 μm and 20 μm. Volcanic and coal-fire dust also absorb in the window region stronger than most of our earlier-investigated more normal aerosol fractions. The data for ammonium sulfate are compared with Remsberg’s measurements on an aqueous solution.
© 1973 Optical Society of America
Original Manuscript: September 7, 1972
Published: March 1, 1973
Frederic E. Volz, "Infrared Optical Constants of Ammonium Sulfate, Sahara Dust, Volcanic Pumice, and Flyash," Appl. Opt. 12, 564-568 (1973)