Crystallographic image processing for scanning probe and transmission electron microscopy

The common practice of Crystallographic Image Processing (CIP) in both electron crystallography and high resolution transmission electron microscopy (HRTEM) of crystals is briefly compared to the crystallographic processing of 2D periodic Scanning Probe Microscopy (SPM) images. With no counterpart in either electron crystallography or HRTEM, the symmetrization of blunt Scanning Tunneling Microscopy (STM) tips is a particularly interesting case of the application of CIP to SPM images of 2D periodic arrays of highly symmetric molecules on crystal surfaces. Such a symmetrization is briefly shown for a regular array of fully fluorinated cobalt phthalocyanine molecules on highly (0001) oriented pyrolytic graphite. On the basis of 2D periodic and preferentially highly symmetric calibrations samples, the point spread function (PSF) of a microscope for a prevailing set of experimental conditions can be extracted by an extension of CIP that has so far only been used for scanning probe microscopy. As long as they were taken under essentially the same experimental conditions, previously or subsequently recorded images can be corrected by convolutions with the inverse of this function. The proposal is made to utilize a single layer graphene support on a Transmission Electron Microscopy (TEM) grid as an internal plane symmetry reference standard for aberration- corrected highest resolution TEM imaging.