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Sunlight Initiated Photochemical Production of
High-Energy Compounds From Environmental Targets

A promising strategy to harvest the energy of solar photons is to generate energy rich fuels through photochemical reactions.  Most common photochemical reactions are initiated through electronic transitions of molecules that occur in the UV spectral region.  Visible light is very much more abundant in the solar spectrum but is not in the correct wavelength range to excite molecular electronic transitions and, so, it is not generally considered an effective driving force in chemistry.

Red solar photons capable of exciting vibrational overtone transitions in the ground electronic state of organic molecules readily penetrate the Earth’s atmosphere.  In the atmosphere, rapid oxidation by OH, O3, NO3 etc. of biogenic and anthropogenic emissions produces oxidized organic (acids, alcohols) and inorganic (HNO3, H2SO4) compounds.  Such hydrophilic molecules hydrogen bond readily to water forming complexes (hydrates) and aggregates.  These make readily available inexpensive targets for solar photochemistry.  

We propose to investigate sun-light initiated photo-reduction reactions of readily available atmospheric targets.  The result of this chemistry is the conversion of highly oxidized organic compounds to reduced, high-energy products.  The broader impact of the proposed fundamental work is to find new paradigms for solar photochemistry with implications to  renewable energy and to new chemistry mediated by water.  Intellectually the merit of this work is to bring fundamental chemical approaches to bear on production of renewable energy.

Publications:

1. "Characterization of the nitric acid-water complex in the infrared and near-infrared region at ambient temperatures in carbon tetrachloride." M. K. Maron, M. J. Shultz and V. Vaida Chemical Physics Letters, 473(4-6), 268-273 (2009).

Instruments:

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