HIGH-RESOLUTION ELECTRON-ENERGY-LOSS SPECTROSCOPY INVESTIGATION OF THE COPPER POLYPHENYLQUINOXALINE INTERFACE FORMATION

The interface formation between copper and polyphenylquinoxaline (PPQ) is investigated. High Resolution Electron Energy Loss Spectroscopy (H REELS) is used to determine the adsorption sites of the first incoming copper atoms onto the surface of the cured polymer. A broadening of t he elastic peak during the first step of the metallization testifies t o the interaction of Cu atoms on the polymeric surface. At low coverag e, the aromatic groups of the PPQ are affected by the copper atoms as the intensity of the vibrational CH-ring stretching mode (at 3022 cm(- 1)) slowly decreases together with the intensity of the loss feature n ear 804 cm(-1) (out-of-plane deformation of the aromatic CH groups). A further metal deposition reduces the intensity of the loss feature lo cated around 1100 cm(-1) (in-plane bending mode of the aromatic CH gro ups). It is worth noting that none of the peaks observed in the virgin polymer disappears completely after metallization. Heating of the met allized polymer restores the intensity of these last two loss features at 800 and 1100 cm(-1), supporting a diffusion of the Cu atoms into t he bulk of the polymer, as previously observed by X-ray Photoelectron Spectroscopy.