Inelastic electron tunneling spectroscopy of phenol and hydroquinone chemisorbed on alumina

Inelastic electron tunneling spectroscopy has been used to probe the irreversible chemisorption of C6H5OH and 1,4-C6H4(OH)2 on a thin amorphous film of Al2O3. This spectroscopy yields a representation of the vibronic excitations of the chemical bonds in the adspecies, i.e., the tunneling spectra are analogous to ir spectra. The C6H5OH is found to adsorb predominately as C6H5O− with a small amount of adsorption as C6H5OH. The 1,4-C6H4(OH)2 is found to adsorb predominately as C6H4(OH)O− and perhaps to a smaller extent as C6H4O22−. Extensive hydrogen bonding is observed among adsorbates and between adsorbates and the hydroxylated alumina surface.