Dark-field microscopy sample preparation

Dark-field electron microscopy (in which the image is formed from the scattered beam), when combined with improved techniques of sample handling and preparation and minimal radiation exposure, can lead to images of sufficiently undamaged DNA at a resolution of 10 A (116). Figure 45 shows such an image in which the two-dimensional projection of the helix is clearly visible on the undamaged part of the molecule. 

This chapter includes a review of the recent literature on polymer microscopy. The basic principles and current challenges of the techniques, as well as the experimental aspects of sample preparation and observation are reviewed elsewhere [1-8]. Specific techniques are surveyed in other reviews for instance TEM [9], SEM [10], Field emission SEM [11], and high angle annular dark field (HAADF)-STEM [12]. 

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