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Atmospheric Processing of Methylglyoxal and Glyoxal in Aqueous Environments

The dicarbonyl molecules glyoxal and methylglyoxal are ubiquitous in the atmosphere, being produced from numerous volatile organic compounds (VOCs) of both biogenic and anthropogenic origin (e.g. isoprene and toluene). While the gas phase chemistry of these dicarbonyls is fairly well understood, there is increasing evidence that they also take part in aqueous phase photo-chemistry, of both clouds and aerosols, leading to the eventual production of organic acids (pyruvic, oxalic) whose origin is currently not well understood. After hydration, red solar photons can excite OH vibrational overtones of methylglyoxal, glyoxal, and their hydrates, leading to the formation of new products through dehydration, decarboxylation, or decarbonylation.

My experimental approach will employ Fourier-Transform spectroscopy and cavity ring down spectroscopy to investigate the gas-aqueous equilibrium and OH vibrational overtones of methylglyoxal, glyoxal and their hydrates and characterize gas phase reagents and products in the laboratory. The photochemical reactions will be investigated using excitation with both laser and conventional solar simulators and will be extended to organic species in condensed water, ice, and water-air interfaces.

Publications:

3. "Gas-phase water-mediated equilibrium between methylglyoxal and its geminal diol." J. L. Axson, K. Takahashi, D. O. De Haan and V. Vaida Proceedings of the National Academy of Sciences of the United States of America, 107(15), 6687-6692 (2010).

2. "Dynamics and spectroscopy of vibrational overtone excited glyoxylic acid and 2,2-dihydroxyacetic acid in the gas-phase." K. Takahashi, K. L. Plath, J. L. Axson, G. C. Nelson, R. T. Skodje and V. Vaida Journal of Chemical Physics, 132(9), Art. Number 094305 (2010).

1. "Gas-phase vibrational spectra of glyoxylic acid and its gem diol monohydrate. Implications for atmospheric chemistry." K. L. Plath, J. L. Axson, G. C. Nelson, K. Takahashi, R. T. Skodje and V. Vaida Reaction Kinetics and Catalysis Letters, 96(2), 209-224 (2009).

Instruments:

Bruker FT-IR Spectrometer
- Tensor
- IFS 66v/S

Cavity Ring Down (CRD)