Around the world, forests and grasslands are being cleared for agriculture. Increasingly, the biomass being produced by this clearing is being burned, adding to the atmosphere carbon dioxide, carbon monoxide, methane and other hydrocarbons, nitric oxide, nitrous oxide, organic acids, inorganic acids and atmospheric particulates and aerosols. This process may be a significant driver of global atmospheric and climate change.
One especially problematic group among these pollutants is gas-phase organic acids, a significant but poorly understood class of volatile organic compounds. N.C. A&T physics professor Dr. Solomon Bililign is studying these acids in the atmosphere, and that work was the subject of his address at the University of Connecticut last week when he delivered the Norman Hascoe Distinguished Lecture.
Dr. Bililign’s slides are here. The abstract of his talk:
Work in our laboratory uses two methods, Cavity Ring Down Spectroscopy and Mass Spectrometric methods, to characterize some of the properties of the organic acids and aerosols. The following will be presented in this talk.
(a) Use of cavity ring down spectroscopy to measure absorption cross sections for overtone induced photochemistry (vibrational overtone excitation of an O-H bond in organic acid molecules present in the atmosphere). Overtone excitation has been shown to cause dissociation of molecules leading to OH radical production for several species. Results of for acetic acid and peracetic acid will be presented.
(b) Proposed use of cavity ring down CRD technique to determine the optical properties of aerosols composed of mixtures of different absorbing and non-absorbing species and to determine their complex refractive indices and extinction efficiency and progress in this area will be presented.