The photoelectron x-ray microscope, a possible tool for analytical soft x-ray microscopy.

In the soft x-ray region, different techniques have been recently developed which can give images of biological objects at an intermediate resolution between optical and electron microscopes. At these wavelengths, very little sample preparation is required because the image contrast is directly dependent upon the chemical composition of the sample itself and on the x-ray wavelength. X-ray microscopy can be extended to absorption microanalysis with a similar resolution, provided that the basic microscope can work through a large range of wavelengths. The photoelectron x-ray microscope that we are developing at LURE satisfies this condition. Its principle is to make a contact x-ray image of the object on a plane photocathode and then, to magnify the secondary electron image, into which it is converted, by means of an emission electron microscope. In the present state of the art, the expectable detection limit, for element maps of 0.1 micron resolution, would be near 1% in concentration.