LATTICE LOCATION OF TRACE-ELEMENTS WITHIN MINERALS AND AT THEIR SURFACES WITH X-RAY STANDING WAVES

The x-ray standing waves generated by dynamical Bragg diffraction were used to directly measure lattice locations of trace elements within a nd at the surface of a mineral single crystal. These high-precision me asurements were made on natural Iceland spar calcite cleaved along the (<10(1)over bar 4>) plane and reacted with a dilute aqueous lead solu tion. Within the bulk crystal, naturally occurring trace manganese was found within (<10(1)over bar 4>) planes, consistent with its substitu tion for calcium. At the crystal surface, sorbed lead was found to be highly ordered and mostly within (<10(1)over bar 4>) planes. This demo nstrates a powerful application of synchrotron radiation in the earth and environmental sciences.