Formation and oxygen intercalation of vitreous 2D silica bilayer films on Ir(111)

Ultrathin 2D silica bilayer films have been reported on several platinum-group metals, namely Ru, Pd, Pt, and Rh. Here, we report the growth of a 2D silica bilayer on Ir(111). The Ir(111) surface shows affinity towards forming a 2D silica bilayer, even at partial coverages of deposited Si. The resulting 2D silica film exhibits a vitreous structure, with apparent heights of 3 Å, as measured by scanning tunneling microscopy. Only the strongest Raman-active mode of 2D silicas, the asymmetric Si-O-Si bending mode at a Raman shift of 1045 cm^-1, is observed, with indications of quenching due to a proposed electronic film-metal coupling. The photoelectron spectra are in good agreement with previous studies of 2D silica bilayer films on other platinum-group metals. Reversible intercalation of O-atoms at the silica-Ir(111) interface is demonstrated and is shown to affect the peak positions in photoelectron spectra of the 2D silica film, confirming an electronic film-metal interaction.