KINETICS OF FIELD EVAPORATION, A STUDY OF MOLECULES IN HIGH ELECTRIC FIELDS

Abstract

Field Evaporation, the physical phenomenon harnessed in the atom probe microscope, describes the breaking apart of molecules in an electric field. Interest has shifted away from the well understood field evaporation of metals and towards a variety of semiconducting and insulating materials for which less is known. One such material commanding current interest is that of polymer self assembled monolayers due to their ability to provide coatings to arbitrary materials giving them novel chemical properties. Stoffers, Oberdorfer and Schmitz in [1] studied experimentally the field evaporation of both amino-undecanethiol and perfluoro-decanethiol SAMs which are the focus of this theoretical investigation. Density functional theory is used to study the process of field evaporation itself along with trends such as electrostriction, charge transfer, polarizability and HOMO/LUMO gap leading up to the point of evaporation. Applying this theory to structures in electric fields on the order of volts per angstrom has given results that form the cornerstone of our theoretical understanding and investigation in this area. For further understanding, a complementary kinetic theory of field evaporation [2] first developed for metals is also implemented which provides both time and temperature dependence. A better understanding of the ion yield is reached with the comparison between possible field evaporated species.