A new area that our research group is exploring has to do with solar-powered, self-cleaning surfaces, such as the external windows of a building. It has been known for some time that semiconductor coatings can be used for photo-catalyzed reactions that are effective in oxidizing organic compounds, thus making the surface self-cleaning. Likewise, some of these semiconductor surfaces have more recently been found to transition from hydrophobic to hydrophilic in the presence of UV light, allowing rainwater to more effectively clean the surface. In our group, MS ChBE student Harika Vakkantula has been studying the surface reconstruction mechanisms of TiO₂ films deposited by atomic layer deposition (ALD). She has been using a combination of reaction path analysis to understand the chemical mechanisms at work in the hydrophobic/hydrophilic transition and has been assessing the effectiveness of different ALD processes at producing films that demonstrate this transition.