A photoelectron spectroscopic study of the interface formation between chromium and a palladium-intercalated polymer film

Synchrotron radiation excited photoemission was used to investigate the chemical reactions occuring at a metal/polymer interface. Chromium was evaporated onto the surface of a Pd-DEBP [Pd(PBu3)2-CCC6H4C6H4CC −]n film, a π-conjugated palladium-intercalated polymer. The evolution of the core level spectra of the polymer film and the evaporated metal were followed to a nominal thickness of 25 Å of the metal overlayer. The disappearance of the shake-up satellite in the C1s spectra suggests a strong initial interaction between the chronium atoms and the π-system of the DEBP moiety. A new carbide-like C1s signal appears upon increasing the chromium deposition, indicating a charge-transfer reaction from the metal overlayer to the DEBP carbons. An initial formation of a chromium arene π-complex is found; the reactivity of chromium upon further metal deposition leads to a σ-bonded chromium carbide. Moreover, chromium reacts with phosphorus atoms, leading to the formation of phosphide-like species, suggested by the presence of a low BE signal in the P2p spectra.