Surface and interface dynamics

Gases in contact with the surfaces of a solid will modify them leading to their pasivation, such as hydrogen in contact with silicon, or corrode them, such as oxygen or sulfur in contact with metals. Solid surfaces can also act as catalysts for chemical reactions, e.g. platinum alloys can oxidize carbon monoxide to carbon dioxide and certain iron ores can turn atmospheric nitrogen into ammonia fertilizers (Haber-Bosch catalysts). Our theory of adsorption, desorption and surface reactions examines the microscopic basis underlying such processes in order to help develop new catalysts and further optimize existing ones. Polymers are long macromolecules with many identical repeat units. They are used in plastics, paints and as corrosion resistant coatings. We are developing a first principles theory that traces the macroscopic properties of polymers to their underlying microscopic origin. Of interest to us are coatings of implants and their resistance to adsorption of proteins from the blood. More generally we are studying the interaction of polymers with water and their mechanical response. We have developed digital in-line holography into a new microscopic tool with which micron-sized objects, such as defects in solids, debris in jet streams, marine plankton, algae, bacteria etc. can be visualized in three dimensions. The motion of many such objects can be followed simultaneously as a function of time visualizing their tracks in 3D.