Metal−Organic Chemical Vapor Deposition of Palladium:  Spectroscopic Study of Cyclopentadienyl-allyl-palladium Deposition on a Palladium Substrate

The deposition and subsequent decomposition of a cyclopentadienyl-allyl-palladium precursor on a Pd(111) single crystal was investigated by a combination of X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Because the precursor decomposes readily on metal surfaces, a deposition system with its inner surfaces completely covered by chemically inert materials such as glass or Teflon was used to keep the precursor molecules intact prior to the deposition process. Upon adsorption on the palladium substrate surface, the precursor molecules are chemically modified even at temperatures as low as 170 K. At higher temperatures, the precursor decomposes, the oxidation state of the palladium changes from +2 to 0, and the ligands remain adsorbed at the palladium surface. Attempts to remove the hydrocarbon ligands by etching with molecular hydrogen were not successful.