X-RAY HOLOGRAPHY WITH ATOMIC RESOLUTION Miklós Tegze and Gyula Faigel Research Institute for Solid State Physics, H-1525 Budapest, P.O.Box 49, Hungary.

One of the basic problems in crystallography is that in the conventional diffraction experiments only the intensity of the scattered radiation is recorded, its phase is lost. In holography [1], the scattered radiation is mixed with a reference wave and the resulting interference pattern is recorded. The hologram contains both the intensity and the phase information and the three dimensional image of the object can be reconstructed. The most important limitation of this imaging technique is the spatial resolution, which is given by the wavelength and/or by the source size. In the last decade the introduction of soft x-ray instead of visible light tremendously improved the resolution which reached a few hundred angstrom [2]. An other line in holography, based on the inside source concept, was suggested recently [3]. We have applied this concept for the case of fluorescent x-rays emitted by a single crystal. We were the first to demonstrate theoretically [4] and experimentally [5] the feasibility of x-ray holography with atomic resolution. We have recorded the holograms of different crystals and successfully reconstructed the three dimensional order of the atoms.

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[2] M. Howels, C. Jacobsen, J. Kirz, R. Feder, K. McQuaid and S.Rothman, Science 238, 514 (1987).

[3] A. Szöke, in Short Wavelength Coherent Radiation: Generation and Applications, T. Attwood, J. Booker (eds), AIP Conference Proceedings No. 147, New York (1986).

[4] M. Tegze and G. Faigel, Europhys. Lett. 16, 41 (1991).

[5] M. Tegze and G. Faigel, Nature (1996, in print).