Quantitative Electron Holography of Macromolecular Structure

Abstract

Abstract : The principal theme underlying this ARO-funded research is the development and application of quantitative electron-optical methods to measure polymer morphology at nano and meso length scales where traditional TEM methods based on differential heavy-element staining techniques fail. This research has developed and implemented phase-contrast imaging methods based on transmission electron holography and chemical imaging methods based on spatially resolved electron energy-loss spectroscopy. Among the compelling basic issues associated with these approaches are the identification of appropriate electron-polymer interactions (mean inner potential, valence and core-electron spectral fingerprints) as well as the response of virgin polymers to the ionizing radiation associated with a 100-200 keV electron beam. These techniques have been applied to a range of problems which require spatial resolution and spectral sensitivity not afforded by other approaches (e.g. optical, X-ray, neutron, etc.). Among the notable achievements of this work has been the determination of the nature of the epoxy-adherend interphase (in collaboration with Dr. S. McKnight, ARL) and the measurement of fast secondary electron damage profiles relevant to both electron microscopy and to e-beam nanolithography.