Investigation of the Interfaces of Tris-(8-hydroxyquinoline) Aluminum with Ag and Al Using Surface Raman Spectroscopy
journal contributionposted on 20.03.2008, 00:00 by Robert J. Davis, Jeanne E. Pemberton
Surface Raman spectroscopy in ultrahigh vacuum is used to interrogate interfaces formed between tris-(8-hydroxyquinoline) aluminum (Alq3) and vapor-deposited Ag and Al. Vapor deposition of Ag onto Alq3 films results in preservation of the Alq3 structure with evolution of simple surface enhancement of Alq3 spectral intensities. Changes in the relative intensities of ring breathing and ring stretching modes of Alq3 upon deposition of Ag are consistent with weak interaction of Ag with the conjugated ring of the ligand. In contrast, vapor deposition of Al onto Alq3 films results in the appearance of new vibrational modes, but only for Al coverages >10 Å mass thickness, consistent with the formation of an Al−Alq3 adduct. At these coverages, slight surface enhancement of spectral intensities is also observed along with growth of several broad modes consistent with partial graphitization of the organic film.