IN-SITU X-RAY-ABSORPTION SPECTROSCOPY INVESTIGATION DURING THE FORMATION OF COLLOIDAL COPPER

The reduction of [N(octyl)(4)](2)[CuCl2Br2] in organic solution (tolue ne) using Li[BEt3H] leads to colloidal Cu protected by cationic surfac tants (NR4+). According to HRTEM (high-resolution transmission electro n microscopy) and UV/vis data, the organosol is composed of relatively large Cu particles with diameters of between 5 and 10 nm. An in situ XANES (X-ray absorption near edge structure) investigation was perform ed for the first time during the colloid synthesis. Our measurements r evealed the formation of an intermediate Cu+ state prior to the nuclea tion of the particles, thus giving direct insight into the mechanism o f the colloid formation. The significant differences between the near edge structures of the bulk sample and the colloidal Cu have to be tra ced back to structural disorder in the lattice of this nanosized mater ial.