Hydroxyl Radical Reaction Animation (VIDEO) University of Pennsylvania This video is under embargo. Please login to access this video. Caption Earth's atmosphere is a complicated dance of molecules. The chemical output of plants, animals and human industry rise into the air and pair off in sequences of chemical reactions. Such processes help maintain the atmosphere's chemical balance; for example, some break down pollutants emitted from the burning of fossil fuels. Understanding exactly how these reactions proceed is critical for predicting how the atmosphere will respond to environmental changes, but some of the steps of this dance are so quick that all of the molecules involved haven't been measured in the wild. A University of Pennsylvania team has now observed one of these rapid atmospheric reactions in the lab. They identify an important intermediate molecule and track its transformation to hydroxyl radicals, also demonstrating the amount of energy necessary for the reaction to take place. Here, a hydrogen atom from one end of the intermediate molecule transfers over and bonds to an oxygen atom on the other side. The molecule then breaks apart, resulting in a hydroxyl radical. Credit University of Pennsylvania Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.