STRUCTURE DETERMINATION OF MICROMETER AND SUBMICROMETER SINGLE CRYSTALS WITH SYNCHROTRON RADIATION. Neder, R. B., Burghammer, M., Grasl, T., Schulz, H., Institut für Kristallographie und Mineralogie, Universität München, Theresienstr.41, 80333 München, Germany
We have mounted individual submicrometer sized single crystals of kaolinite to thin glass fibers. We developed a novel micromanipulator for usage within a scanning electron microscope. This micromanipulator uses a combination of stepper motor controlled microtranslation units with piezo drives and is capable of nanometer resolution. The glass fiber supports are pulled from massive glass rods to a diameter of 0.5 um.
The sample volume is estimated at < 0.1 um3. Diffraction experiments are carried out at the microfocus beamline, ESRF, under vacuum conditions. The combination of a vacuum chamber and submicrometer sized sample-supports effectively reduces the experimental background.
As another example we present the results of the determination of hydrogen positions from a hydrous barium oxalate. Despite the presence of a heavy metal, the positions, as well as, thermal parameters of the hydrogen could be refined.
A third example is optically anomalous topaz. An individual microcrystal was prepared from within an optical zone. Single crystal diffraction experiments at the ESRF were carried out on a crystal of 2 um3 volume.