The photocatalytically-driven oxidation of isoprene by titanium dioxide (TiO2) has environmental implications associated with microclimate formation and tropospheric ozone production. Isoprene (C5H8) is a conjugated diene compound introduced into the atmosphere by natural processes from both plants and animals. The emission of isoprene from plants alone generates more atmospheric hydrocarbons than all other non-methane anthropogenic hydrocarbons. TiO2 is a photocatalytic particle found in the atmosphere as dust, with 0.1 - 10% mass mixing ratios depending on the location, as well as on stationary surfaces in contact with the atmosphere, such as building exteriors. The intermediates of this photooxidation reaction can take part in many different reactions, making it difficult to predict the atmospheric impact of isoprene. Since the oxidation products of isoprene, which includes ozone, can be hazardous to humans, it is important to study this reaction and determine the effect of this photocatalyst on the rate of the reaction. We report the results of studies on isoprene interactions with titanium oxide cluster anions as models for photocatalytic oxidation of isoprene on defective surfaces using mass spectrometry and anion photoelectron imaging. Results show that OH-isoprene complex, which initiates reactions leading to O3 formation, is formed. An exploration of additional complexes formed in these reactions will be presented.

Modeling photocatalytic oxidation of isoprene on mineral surfaces using TixOy + isoprene cluster reactions

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