Molecular Imaging in High Electric Fields

Abstract

For the past thirty years, attempts have been made to use the field-electron emission microscope (FEEM), and the field-ion microscope (FIM) to image organic molecules. These attempts were inspired by the simplicity of the techniques and the potential for achieving high image contrast, magnification, and resolution. Since both microscopies rely on direct point projection for imaging, there is no need for electron-lens systems or devices to minimize specimen vibration. As a result, both techniques offer the hope of achieving high quality molecular images with a minimum of effort.In the early 1950's the FEEM was the only microscope which had demonstrated a magnification of 106 at an image resolution better than 2nm. Since it had already been used to image the diffusion of monomolecular films on clean metal surfaces, there was growing optimism that individual organic molecules could be imaged as well. In 1951, striking FEEM patterns of flaventhrene and copper-phthalocyanine were obtained which displayed the known symmetry of each molecule (two-fold and four-fold, respectively). Unfortunately, the success of these experiments was relatively shortlived.