Oxidation of preferentially (111)-oriented Au films in an oxygen plasma investigated by scanning tunneling microscopy and photoelectron spectroscopy

Koslowski, B.; Boyen, Hans‐Gerd; Wilderotter, C.; Kästle, G.; Ziemann, P.; Wahrenberg, R.; Oelhafen, P.

doi:10.1016/s0039-6028(00)00986-9

Cited by 137 publications

(153 citation statements)

References 27 publications

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“…This Au surface oxide is unstable under UHV conditions and in an O 2 atmosphere at 100°C, leaving a clean Au surface when O 3 is removed ( Figure 3.3(iii)), in agreement with a previous study [73] O system, the co-existence of different oxygen species has been predicted by theory [92] and experimentally verified [93,94]. Similar conclusions -i.e.…”

Section: Xps Measurement Performancesupporting

confidence: 91%

“…The formation of Au oxide has been reported, not only for nanoparticles [86,87], but also for extended Au surfaces, such as single-crystals [86] and polycrystalline thin films [73,76,89]. In our case, the ozone treatment at 100 °C resulted in the formation of a surface oxide phase with a thickness of 1-2 atomic layers, instead of the 3-4 nm thick plasma-oxidized thin films reported by others [73,76,90].…”

Section: Xps Measurement Performancesupporting

confidence: 49%

“…In Figure 3 When the O 2 /O 3 mixture was introduced into the chamber and the sample was heated to 100 °C, the Au 4f spectrum changed ( Figure 3.21A(ii)). A well-defined peak appears at 85.6 eV, which is assigned to an ionic Au species [73,76]; however, with lower BE than that of Au 2 O 3 (BE 85.9 eV) [89,104]. Under O 3 the numbers of low coordinated Au atom increasing, this is evidenced by an increase and broadening in low BE peak at 83.…”

Section: Co Oxidation On Au Powdermentioning

confidence: 94%

“…These kinetic energies correspond to inelastic mean free paths (IMFP) of 0. which is assigned to cationic Au species [73,76], together with an additional feature at low BE (83.29 eV). All fitting parameters are given in Table 3.1.…”

Section: Xps Measurement Performancementioning

confidence: 98%

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Is Nanostructuring Sufficient To Get Catalytically Active Au?

et al. 2016

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Gold nanoparticles on transition-metal oxides were synthesized by two different methods: precipitation and photoinduced decomposition of an intermediate gold–azido complex. Only samples prepared by the precipitation method showed significant CO conversion at low temperature. XPS shows the formation of two Au species (Au0 and Auδ+) on the surface of active Au/TiO2 and Au/Fe2O3 samples. The energy shift of the Auδ+ peak depends on the support and is 0.6 and 0.9 eV for Au/TiO2 and Au/Fe2O3, respectively. TEM images indicate the formation of overlayer on Au particles. These results prove Au activation via a strong metal–support interaction, on the basis of the strong influence of the support on the electronic structure of the gold through charge transfer and stabilization of low-coordinated Au atoms.

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Section: Xps Measurement Performancesupporting

confidence: 91%

Section: Xps Measurement Performancesupporting

confidence: 49%

Section: Co Oxidation On Au Powdermentioning

confidence: 94%

Section: Xps Measurement Performancementioning

confidence: 98%

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Is Nanostructuring Sufficient To Get Catalytically Active Au?

et al. 2016

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“…As expected, the Au 2 O 3 is confined to the surface: at larger grazing angle (3.0 • , penetration depth 150 nm), we probe the full sample depth of 100 nm instead of the top 4.2 nm, and we observe no change in the XANES spectrum at any gate voltage (see Supplemental Material [12]). Au 2 O 3 is known to be a semiconductor with a band gap of ∼0.5 eV [26]. Thus, at room temperature, the intrinsic carrier density in Au 2 O 3 is negligible compared to the carrier density in metallic gold.…”

mentioning

confidence: 99%

Mechanism for the large conductance modulation in electrolyte-gated thin gold films

et al. 2014

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Electrolyte gating using ionic liquid electrolytes has recently generated considerable interest as a method to achieve large carrier density modulations in a variety of materials. In noble metal thin films, electrolyte gating results in large changes in sheet resistance. The widely accepted mechanism for these changes is the formation of an electric double layer with a charged layer of ions in the liquid and accumulation or depletion of carriers in the thin film. We report here a different mechanism.In particular, we show using x-ray absorption near edge structure (XANES) that the previously reported large conductance modulation in gold films is due to reversible oxidation and reduction of the surface rather than the charging of an electric double layer. We show that the double layer capacitance accounts for less than 10% of the observed change in transport properties. These results represent a significant step towards understanding the mechanisms involved in electrolyte gating.

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Micellar Nanoreactors—Preparation and Characterization of Hexagonally Ordered Arrays of Metallic Nanodots

Kästle

Boyen

Weigl

et al. 2003

Adv Funct Materials

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The preparation of hexagonally ordered metallic nanodots was studied in detail with emphasis on the chemical state of the resulting particles. To obtain these dots, in a first step micellar structures were formed from diblock copolymers in solution. The reverse micelles themselves are capable of ligating defined amounts of a metal salt within their cores, acting as nanoreactors. After transfer of the metal‐loaded reverse micelles onto a substrate, the polymer was removed by means of different plasmas (oxygen and/or hydrogen), which also allow the metal salt to be reduced to the metallic state. In this way, ordered arrays of metallic nanodots can be prepared on various substrates. By adjusting the appropriate parameters, the separation and the size of the dots can be varied and controlled. To determine their purity, chemical state, and surface cleanliness—all of which are crucial for subsequent experiments since nanoscale structures are intrinsically surface dominated—in‐situ X‐ray photoelectron spectroscopy (XPS) and ex‐situ transmission electron microscopy (TEM) were applied, also giving information on the formation of the nanodots.

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Oxidation of preferentially (111)-oriented Au films in an oxygen plasma investigated by scanning tunneling microscopy and photoelectron spectroscopy

Cited by 137 publications

References 27 publications

Is Nanostructuring Sufficient To Get Catalytically Active Au?

Is Nanostructuring Sufficient To Get Catalytically Active Au?

Mechanism for the large conductance modulation in electrolyte-gated thin gold films

Micellar Nanoreactors—Preparation and Characterization of Hexagonally Ordered Arrays of Metallic Nanodots

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