On The Feasibility of Imaging, By High Resolution Electron Microscopy, Isolated Individual Sheets of Graphitic Carbon

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Abstract
SUMMARY: A comparative survey of computer simulated and experimentally obtained images shows that it is feasible to observe, end‐on, isolated single sheets of trigonally bonded carbon atoms in graphitic substances directly by electron microscopy, provided that certain imaging conditions are employed. For a typical commercial instrument (Philips EM300 with a spherical aberration coefficient of 1.6 mm) authentic images are found whenever the objective lens is set at underfocus positions between 65 and 110 nm, with optimum contrast occurring near the ‘Scherzer’ imaging condition of 95 nm underfocus.At this latter focus position the fringe contrast is maximal when the sheet extends in the direction of the electron beam for a distance of about 5.5 nm; but sheets as narrow as 1.0 nm (i.e. containing some four widths of benzene rings in the direction of the electron beam) should be detectable.