Abstract:

Organic compounds are one of the major classes of indoor air pollutants and are emitted from a variety of sources including building materials, cleaning products, and human occupants. The composition and concentrations of these organic compounds can be significantly affected by chemical transformations on indoor surfaces. Given the large surface area-to-volume ratio in the built environment, understanding these chemical processes are critical to understanding indoor chemistry. However, the detailed molecular interactions between organic compounds and indoor surfaces are still poorly understood. By using force field-based and ab initio molecular dynamics simulations, we are able to gain an atomistic understanding of the interactions between many indoor relevant organic compounds including cyclic monoterpenes and oxygenated organic species on two indoor relevant surfaces, SiO2 and TiO2. Our results indicate a range of interaction strengths for the adsorption of organic compounds on these surfaces coming from factors including the orientation of the molecule on the surface and the location of Csp2 carbon centers or oxygen atoms in the adsorbate. Our results are supported by experimental validation via infrared spectroscopy, where we see similar trends between our calculated ab initio power spectra of these molecules on the surface and the experimentally determined IR spectra.