A RAMAN-SPECTROSCOPIC STUDY OF THE POLYIMIDE AG(110) INTERFACE

We have investigated the bonding of the monomers pyromellitic dianhydride (PMDA) and oxydianiline (ODA) and their subsequent polymerization to form polyimide on Ag(110) in ultrahigh vacuum. Unenhanced surface Raman spectroscopy was used to identify adsorbed species and to follow the polymerization reaction. ODA was unreactive on the cold (140 K) surface; spectral features were identical to those in the condensed multilayer indicating that the monolayer is physisorbed. PMDA, on the other hand, adsorbed dissociatively, the evidence being consistent with a bidentate surface carboxylate mode of bonding. Finally, heating a 30 Å film of codosed monomers to 473 K resulted in the formation of a polyimide film as shown by characteristic features in the carbonyl stretching region of the Raman spectrum. © 1990.