Inelastic electron tunnelling spectroscopy of 1,3-diketones and related molecules on plasma-grown aluminium oxide

Abstract

Inelastic electron tunnelling (IET) spectra are reported for 2,4-pentanedione and other 1,3-diketones, β-ketoester, methyl-2-hydroxybenzoate and 2-hydroxybenzaldehyde adsorbed from the vapour on to plasma-grown aluminium oxide. These adsorbates are shown to exist as the corresponding anions chelated to surface-exposed aluminium cations with the chelate ring held approximately perpendicular to the local surface. The IET spectrum of the corresponding 2,4-pentanedione: magnesium-oxide surface complex is also discussed as is the surface protonation–dehydration reaction which leads to the formation of the chemisorbed chelates.