1. Röntgenographie; Max Planck Institute for Solid State Research; Heisenbergstr. 1 70569 Stuttgart Germany
2. Photon Science (FS-PE); Deutsches Elektronen-Synchrotron; FS-PE, Notkestr. 85 22607 Hamburg Germany
3. Dept. of Chemistry; University of California; Berkeley CA 94720-1460 USA