The interphase between a polyimide and a metal substrate was modeled by depositing phthalic anhydride (PA) onto a gold substrate pretreated with 4-aminophenyldisulfide (APDS) and then curing in a mixture of acetic anhydride and pyridine or triethylamine. Surface-enhanced Raman scattering (SERS) and reflection-absorption infrared spectroscopy (PAIR) were used to characterize the model interphases. It was found that APDS was adsorbed dissociatively onto Au substrates through the sulfur atoms. The average tilt angle for APDS molecules adsorbed onto gold substrates was determined, using RAIR, to be approximately 46 degrees. However, there was no preferred rotational angle of the adsorbed APDS molecules about the long molecular axes. When PA was deposited onto APDS-primed Au substrates, anhydride groups of PA reacted with amino groups of APDS to form amic acids. Curing these thin amic acid films in acetic anhydride catalyzed with pyridine produced mainly isoimide species, while curing in the presence of triethylamine gave imide as the major product. The relative amount of isoimide and imide thus depended strongly on the catalyst used in the chemical curing processes.