Magnification Determination for High Resolution Electron Microscopy

Abstract

Modern electron microscopes provide film magnifications of X300,000 and higher at resolutions levels below 5 A. However, on these same microscopes it is difficult to obtain a magnification calibration of better than ± 5%, the value given by most microscope manufacturers for the reproducibility of their lenses.The following internal calibration procedure was developed that provides a magnification calibration of ± 1.6% at the 95% confidence level. The procedure utilized a graphitized ISAF carbon black specimen described in detail by Heidenreich et al.1 (see Figure 1). The particles of this calibration sample contain ordered carbon layer planes having an interplanar spacing (d002) o f 3.44 A, as measured by X-ray diffraction. In addition, these layer planes conform to the carbon particle contours and contain a large number of distortions, including curved and bent layer planes and various types of dislocations.