Physics and Chemistry in High Electric fieldsElectric fields of the order of volts per angstrom effect the electronic structure of atoms and molecules and are used in the field ion microscope and also in the tunneling microscope to alter reaction pathways and to manipulate adsorbates. In the mid-1980's extended Hückel-type calculations have been used to show that even Helium can undergo field-induced chemisorption. Now density functional theory is used to understand field-induced chemistry at surfaces including the kinetics of chemical oscillations. An example of a recent calculation is the decomposition of polythiophene when it is subjected to fields of about 1.4 V/Å. The picture shows the gradual breakup of a short segment of polythiophene, which has important applications in the field of organic semiconductors, as gate voltages may effect the operational stability of photovoltaic devices.