Soft x-ray microscopy.

Soft x-ray microscopes are beginning to provide information to complement that obtained from optical and electron microscopy. Soft x-ray microscopy can deliver 30-nm resolution images of hydrated cells up to approximately 10 microns thick, and efforts towards obtaining higher resolution are under way. Although living specimens cannot be studied readily except in single exposures, fixed samples can be imaged at high resolution, and flash-frozen specimens can be studied without chemical modification and without significant radiation damage. Tomography is being developed for 3-D imaging, and spectromicroscopy offers unique capabilities for biochemical mapping of unlabelled structures beyond those of gold and fluorescent labels. Currently, most soft x-ray microscopes operate at synchrotron radiation facilities, but laboratory-scale microscopes are being developed too.