Mineral dust aerosol can impact the chemistry and climate of the Earth's atmosphere by providing surfaces for heterogeneous reactions and modifying the radiative balance of the Earth, respectively.  Surface/gas reactions can alter the chemical composition of the mineral surfaces, thereby modifying the chemical and radiative properties of the mineral aerosol.  To study the heterogeneous chemistry of mineral dust aerosol at atmospherically relevant relative humidities, a transmission Fourier transform infrared (FT-IR) spectrometer equipped with an Aabspec #S reaction chamber in line with an annular denuders has been previously designed, developed and characterized.  Studies of formic acid uptake on various dusts and dust analogs will be presented. Gas phase formic acid was extracted in the form of formate from the annular denuders and quantified off line by ion chromatography (IC). Changes in the condensed phase reaction products were monitored using FT-IR spectroscopy and quantified by extraction and analysis by IC. Infrared spectral features are identified and compared to calculated vibration frequencies of formic acid on silica.

Study of the heterogeneous chemistry of formic acid on mineral dusts by dual chamber transmission FT-IR flow reaction system

245th National Meeting (2013)

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