Infrared absorption spectra of atmospheric dust over an interior desert basin

Summary Based on the qualitative microspectrophotometric analysis of 287 atmospheric dust samples taken within the surface boundary layer over south central New Mexico, U.S.A. from May 1966 through October 1967, a representative infrared absorption spectrum from 4000 to 250 cm^–1 (2.5 to 40 m) is presented. The strongest absorption band is centered at 1027 cm^–1 (9,7 m), within the 1250 to 770 cm^–1 (8 to 13 m) atmospheric window, and is silicate induced. Two other strong broad absorption bands are the carbonate band at 1425 cm^–1 (7.0 m) and the silicate band at 468 cm^–1 (21.4 m). Temporal variations in the absorption spectra of the dust are observed primarily in the varying relative intensities of the 1027 and 1425 cm^–1 (9.7 and 7.0 m) absorption bands and in the occasional enhancement of the 1027 cm^–1 (9.7 m) band caused by sulfates in the dust. This study indicates that there is a close similarity between the absorption spectra of the atmospheric dust and the spectra of the small particle fraction of area soils, and between the representative dust spectrum and a spectrum of a synthetic mixture (by weight) of 80% silicates, 16% carbonates, and 4% nitrates.