This grant supports efforts by Vicki Grassian, Distinguished Professor of Physical Chemistry at the University of California, San Diego, to monitor the chemistry that occurs on indoor surfaces. Grassian and her team will compare surface adsorption and surface reactions (kinetics, extent of reaction) over a range of different types of material surfaces found in homes, offices, and public spaces, including glass (windows), titanium dioxide (paints and self-cleaning surfaces), concrete, and drywall. She will conduct these experiments on model systems to better understand the chemistry of these materials, as well as on surfaces coated with thin films to determine if they behave differently. Gases of interest include ozone, nicotine, cyclomethylsiloxanes (components of personal care products), ammonia, and co-mixtures of these. In addition, Grassian will conduct a series of controlled experiments that vary the relative humidity, temperature, and light surfaces are exposed to, and measure how chemical reaction mechanisms and reaction kinetics vary across cases. An important aspect of this research is to understand how these factors drive the chemistry of indoor surfaces with gases present in indoor environments. They plan to probe the molecular processes that occur on these indoor surfaces using molecular-based probes such as X-ray photoelectron spectroscopy, vibrational spectroscopy, and scanning probe techniques such as atomic force microscopy. This project will characterize many of the physical and chemical transformations taking place on indoor surfaces and generate new data for indoor chemistry models. This proposal will provide a molecular-level understanding of chemistry on indoor surfaces as affected by important factors such as organic coatings, light, and relative humidity. The results will be shared through peer-reviewed publications and presentations at conferences and meetings. At least two students and one postdoc will be trained.