Determination of surface OH acidity from the formation of acid/base complexes on ultrathin films of γ-Al2O3 on NiAl(100)

H2O Dissociation-Induced Aluminum Oxide Growth on Oxidized Al(111) Surfaces

“…In particular, the mechanism of the reaction of water with oxide surfaces has been a subject of intensive study because of the widespread use of oxides as catalysts, catalyst supports, and promoters. , Much of the study has been focused on the surfaces of bulk oxides for understanding the effect of surface structures and surface defects on the dissociation of H 2 O molecules. Generally, H 2 O adsorbs molecularly at a perfect oxide surface while dissociatively at a nonperfect oxide surface (i.e., surface defect sites). − More recently, there have been extensive studies of H 2 O adsorption on ultrathin aluminum oxide films formed on Al or NiAl surfaces under ultrahigh vacuum (UHV) and non-UHV conditions, − where the oxide films serve as a surface-science substitute for macroscopically sized single crystals of alumina that typically prohibit the application of surface sensitive tools based on the interactions of matter with charged particles (e.g., electrons and ions). Ultrathin oxide films on metal supports, which can be considered as an “electrically conductive” counterpart of insulating bulk oxides, represent a unique combination of material systems with distinct properties that rely critically on the thickness of the oxide films.…”

On the use of EDA background error variances in the ECMWF 4D‐Var

“…Modification of oxide surfaces with organo phosphonic acid (PA)‐based molecules have attracted increased interest in recent years for their moisture stability and lack of homocondensation 5. PA molecules efficiently covalently bind to metal oxides following an acid‐base condensation and coordination mechanism where acidic PA headgroups (p K a ≈ 2) readily react with more basic metal hydroxyl (M–OH) groups (p K a ≈ 6–9 for many metal oxides)6, 7 resulting in stable P–O–M phosphonates (≈30–70 kcal mol −1 adsorption energy8). 5 However, phosphonate SAM formation on SiO 2 has proven to be more difficult to achieve.…”

“…For example, simple approaches to modify SiO 2 with PA molecules by immersion assembly,9, 10 spin‐casting,11, 12 or microcontact printing (μCP)13 have resulted in PA headgroups physisorbed to SiO 2 through H‐bonding (≈10–20 kcal mol −1 bond energy)14 or having poorly defined phosphonate coverage. This may be ascribed to silanol groups (Si‐OH) being relatively acidic (p K a ≈ 4.5)15 and the sensitivity of P–O–Si bond formation to hydrolysis 5–10. In order to form stable P–O–Si phosphonates on SiO 2 , 48 h of solid‐state thermal annealing of PA films at 140 °C has been employed 9–16.…”

Spin‐Cast and Patterned Organophosphonate Self‐Assembled Monolayer Dielectrics on Metal‐Oxide‐Activated Si

“…[3, 4] Modification of oxide surfaces with organo phosphonic acid (PA)-based molecules have attracted increased interest in recent years for their moisture stability and lack of homocondensation. [5] PA molecules efficiently covalently bind to metal oxides following an acid-base condensation and coordination mechanism where acidic PA headgroups (p K a ∼2) readily react with more basic metal hydroxyl (M-OH) groups (p K a ∼6-9 for many metal oxides) [6, 7] resulting in stable P-O-M phosphonates (∼30-70 kcal mol −1 adsorption energy [8] ). [5] However, phosphonate SAM formation on SiO 2 has proven to be more difficult to achieve.…”

“…μCP of 3 compared to 2 resulted in higher-quality subsequent patterning of 1 and solution processed semiconductors, likely from the lower surface energy of 3 ( vide supra ). Patterned p -channel devices using 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS-Pen) and n -channel devices using [6,6] -phenyl-C61-butyric acid methyl ester (PCBM) showed stable switching characteristics and negligible hysteresis at sub-2V driving voltages (Fig. 4c and Fig.…”