Characterization of the interface between metal and tris (8-hydroxyquinoline) aluminum using surface-enhanced Raman scattering with glass cap encapsulation

Encapsulation with a glass cover in a dry nitrogen atmosphere after metal deposition is found to be effective for obtaining reproducible and stable surface-enhanced Raman spectra of tris (8-hydroxyquinoline) aluminum (Alq3). Vapor deposition of Au onto Alq3 films shows enhanced Raman bands of neutral Alq3, whereas deposition of Ag results in the appearance of new vibrational modes assigned to radical anions of Alq3. The Raman intensity of the encapsulated sample was stable for 2 months. The effect of the insertion of a sub-nm layer of LiF, Mg, or Al between the deposited Au and the Alq3 layer is also investigated.