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Light-absorbing secondary organic material formed by glyoxal in aqueous aerosol mimics

Shapiro, E. L.; Szprengiel, J.; Sareen, N.; Jen, C. N.; Giordano, M. R.; McNeill, Vivian Faye

Light-absorbing and high-molecular-weight secondary organic products were observed to result from the reaction of glyoxal in mildly acidic (pH=4) aqueous inorganic salt solutions mimicking aqueous tropospheric aerosol particles. High-molecular-weight (500–600 amu) products were observed when ammonium sulfate ((NH4)2SO4) or sodium chloride (NaCl) was present in the aqueous phase. The products formed in (NH4)2SO4 or ammonium nitrate (NH4NO3) solutions absorb light at UV and visible wavelengths. Substantial absorption at 300–400 nm develops within two hours, and absorption between 400–600 nm develops within days. Pendant drop tensiometry measurements show that the products are not surface-active. The experimental results along with ab initio predictions of the UV/Vis absorption of potential products suggest a mechanism involving the participation of the ammonium ion. If similar products are formed in atmospheric aerosol particles, they could change the optical properties of the seed aerosol over its lifetime.

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Title
Atmospheric Chemistry and Physics
DOI
https://doi.org/10.5194/acp-9-2289-2009

More About This Work

Academic Units
Chemical Engineering
Publisher
European Geosciences Union
Published Here
May 26, 2016