Soft X-ray Contact Imaging at CSRF

Abstract

The advantages of using soft X-rays for the study of ultrastructure in biological materials have been described a number of times (Spiller et al, 1979; Feder et al, 1977) with some emphasis on the potentially high resolutions possible (Sayre et al., 1978) for specimens thick relative to those used for electron microscopy. Because of the large differences in absorption coefficients for elements which are biologically important such as C, N, O, etc., the inherent contrast is good for biological materials, and images can be obtained without the staining so often used in electron microscopy. In addition, the absorption coefficient of water is an order of magnitude smaller than that of protein in the soft x-ray range between the oxygen and carbon edges, pointing out the potential of imaging wet or perhaps even living biological material.