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 occurring at a metal/polymer interface. Chromium was evaporated onto the surface of a Pd-DEBP [Pd(PBu(3))(2)-C equivalent to drop C-C6H4-C6H4-C=C-](n) film, a pi-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 Angstrom of the metal overlayer. The disappearance of the shake-up satellite in the C1s spectra suggests a strong initial interaction between the chromium atoms and the pi-system of the DEEP moiety. A new carbide-like C1s signal appears upon increasing the chromium deposition, indicating a charge-transfer reaction from the metal overlayer to the DEEP carbons. An initial formation of a chromium arene pi-complex is found; the reactivity of chromium upon further metal deposition leads to a sigma-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.