Au Islands Research Articles

The influence of ultrafast laser processing on morphology and optical properties of Au-GaAs composite structure

The results of direct femtosecond laser structuring of GaAs wafer coated with continuous semitransparent gold (Au) film are presented. The obtained structures demonstrate a combination of different features, namely laser-induced periodic surface structures (LIPSS) on semiconductor and metal film, nanoparticles, Au islands, and fragments of exfoliated Au film. The properties of Au-GaAs samples are studied with scanning electron microscopy (SEM), Raman scattering, and photoluminescence (PL) spectroscopy. The behaviour of phonon modes and enhancement of band-edge PL of Au-GaAs composite sample are discussed. The Raman spectra of Au-GaAs sample processed at different levels of irradiation pulse energy reveal forbidden TO and allowed LO phonon modes for selected geometry of experiment, as well as the manifestation of GaAs surface oxidation and amorphization. A 12-fold increase of PL intensity for Au-GaAs sample with LIPSS compared to initial GaAs surface is observed. The detected PL enhancement is caused by an increase of absorption in GaAs due to the light field enhancement near the Au nanoislands and a decrease of nonradiative surface recombination. The blue shift of PL band is caused by the quantum size effect in GaAs nano-sized features at laser processed surface. The combination of GaAs substrate with surface micro- and nanostructures with Au nanoparticles can be useful for photovoltaic and sensorics applications.

Gold intercalation of different 6H-SiC(0001) surface reconstructions

We report on in situ investigation of Au intercalation of different zero-layer graphene surface reconstructions of 6H-SiC(0001): (3×3)R30∘+(63×63)R30∘, (63×63)R30∘+(5×5)R0∘, (63×63)R30∘+(5×5)R0∘+Gr. We show that the most appropriate reconstruction for graphene formation via Au intercalation is a one with some fraction of initial graphene monolayer. A well-ordered epitaxial Au(111) islands on the zero-layer graphene were revealed with the same crystallographic orientation as the SiC surface. Ab initio calculations approve that the value of Rashba splitting in graphene increases with the density of Au atoms per unit cell and with the reduction of average distance between Au and graphene.

The in-plane band bending effect around Au islands grown on the Bi2Te3 topological insulator

We have utilized scanning tunneling microscopy and spectroscopy (STM/STS) as well as x-ray linear dichroism (XLD) along with DFT calculations to determine the structural and electronic changes of the gold-covered nonstoichiometric Bi2Te3 single crystal surface. XLD spectra supported by a numerical simulation of several configurations show that at low coverage (< 1.0 ML) gold forms insoluble islands, while for higher coverage (> 1.0 ML) mixing at the Au/Bi2Te3 interface may occur. For local electronic characterization around stand-alone Au islands, small coverages were selected for which the inter-island distance is large enough to avoid overlapping island-wide effects. STS spectra reveal that for small coverages the topological surface states (TSS) are preserved. However, at a distance of about 10 nm from an Au island, by approaching the islands, the electronic structure gradually changes. This is manifested by a gradual shift of the STS spectra to more negative energies with respect to the pristine surface. The results are discussed in view of possible Au-Bi2Te3 mixing, a local charge transfer and the presence of in-plane downward band bending.

Investigation of biosensing properties in magnetron sputtered metallized UV-curable polymer microneedle electrodes

Direct management and assessment of metal film properties applied to polymer microneedle (MN) biosensors remains difficult due to constraints inherent to their morphology. By simplifying the three-dimensional structure of MNs and adjusting the deposition time, different thicknesses of Au films were deposited on the UV-cured polymer planar and MN substrates. Several properties relevant to the biosensing of the Au films grown on the polymer surfaces were investigated. The results demonstrate the successful deposition of pure and stable Au nanoparticles onto the surface of UV-curable polymer materials. Initially, Au islands formed within the first minute of deposition; however, as the sputtering time extended, these islands transformed into Au nanoparticle films and disappeared. The hydrophilicity of the surface remains unchanged, while the surface resistance of the thin film decreases with increasing thickness, and the adhesion to the substrate decreases as the thickness increases. In short, a sputtering time of 5–6 min results in Au films with a thickness of 100–200 nm, which exhibit exceptional comprehensive biosensing performance. Additionally, MNs made of Au/UV-curable polymers and produced using magnetron sputtering maintain their original shape, enhance their mechanical characteristics, and gain new functionalities. The Au/UV-curable polymer MNs exhibited remarkable electrode performance despite being soaked in a 37 °C PBS solution for 14 days. These discoveries have important implications in terms of decreasing the dependence on valuable metals in MN biosensors, lowering production expenses, and providing guidance for the choice and design of materials for UV-curable polymer MN metallization films.

A rapid field-ready electrical biosensor consisting of bismuthine-derived Au island decorated BiOCl nanosheets for Raphidiopsis raciborskii detection in freshwater.

Cyanobacteria play an essential role in nutrient cycling in aquatic ecosystems. However, certain species adversely affect the environment and human health by causing harmful cyanobacterial algal blooms (cyanoHABs) and producing cyanotoxins. To address this issue, continuous cyanoHAB monitoring has been considered; however, a gold standard has not yet been established. In this study, we aimed to develop a dual DNA-targeting capacitive-type biosensor for rapid field-ready monitoring of Raphidiopsis raciborskii, a causative species of cyanoHAB. To enhance the sensing signal, a plate-like Au-BiOCl nanocomposite was synthesized using a spontaneous carbonation process without additional additives. The alternating-current electrothermal flow (ACEF) technique was applied to enable rapid DNA and probe binding within 10 min. The limits of detection (LODs) for R. raciborskii RubisCO large subunit (rbcL) and RNA polymerase beta subunit (rpoB) genes diluted in deionized (DI) water were 4.89 × 10-17 and 3.89 × 10-17 M, respectively. Furthermore, the LODs of R. raciborskii rbcl and rpoB diluted in freshwater containing HAB were 2.55 × 10-16 and 3.84 × 10-16 M, respectively, demonstrating the field-ready applicability of the device. The fabricated cyanobacterial DNA-sensing platform enabled powerful species-specific detection using a small sample volume and low target concentration without a nucleic acid amplification step, dramatically reducing the detection time. This study has considerable implications for detecting HABs, early warning systems, and species-specific environmental monitoring technology.

Epitaxially Grown Silicon Nanowires with a Gold Molecular Adhesion Layer for Core/Shell Structures with Compact Mie and Plasmon Resonances.

Noble-metal plasmonic nanostructures have attracted much attention because they can support deep-subwavelength optical resonances, yet their performance tends to be limited by high Ohmic absorption losses. In comparison, high-index dielectric materials can support low-loss optical resonances but do not tend to yield the same subwavelength optical confinement. Here, we combine these two approaches and examine the dielectric-plasmonic resonances in dielectric/metal core/shell nanowires. Si nanowires were grown epitaxially from (111) substrates, and direct deposition of Au on these structures by physical vapor deposition yielded nonconformal Au islands. However, by introduction of a molecular adhesion layer prior to deposition, cylindrical Si/Au core/shell nanostructures with conformal metal shells were successfully fabricated. Examining these structures as optical cavities using both optical simulations and experimental extinction measurements, we found that the structures support Mie resonances with quality factors enhanced up to ∼30 times compared with pure dielectric structures and plasmon resonances with optical confinement enhanced up to ∼5 times compared with pure metallic structures. Interestingly, extinction spectra of both Mie and plasmon resonances yield Fano line shapes, whose manifestation can be attributed to the combination of high quality factor resonances, Mie-plasmon coupling, and phase delay of the background optical field. This work demonstrates a bottom-up synthetic method for the production of freestanding, cylindrically symmetric semiconductor/metal core/shell nanowires that enables the efficient trapping of light on deep-subwavelength length scales for varied applications in photonics and optoelectronics.

Electrochemical interfaces between Au(100) and deep eutectic solvents: An in situ scanning tunneling microscopy study

Deep eutectic solvents (DESs) are promising electrolytes for electrochemical fields due to their excellent properties. Electrochemical behaviors of Au(100) electrode in two choline chloride-based DESs ethaline and reline with different hydrogen bond donor molecules have been investigated by cyclic voltammetry and in situ scanning tunneling microscopy (STM). Cyclic voltammograms present three pairs of current peaks for Au(100) electrodes in the two DESs. On the basis of the results of in situ STM, the three pairs of current peaks are assigned to the formation and lifting of Au(100) surface reconstruction, adsorption and desorption of chloride ions, and phase transition of chloride ion adlayer. Compared with Au(111), one extra current peak and the corresponding (√5 × √5)R26.6° ordered adlayer of chloride ions were observed for Au(100) electrode. An order-order phase transition of chloride ion adlayer was observed in ethaline, while an order-disorder phase transition was observed in reline. Furthermore, no Au islands was observed on Au(100) surface in ethaline after the lifting of reconstruction when the potential is moved positively and gradually. However, gold nanowires could form and stably exist on Au(100) surface, which are different from that formed on Au(111) surface in reline. Our results provide detailed insights into the interfacial structures between Au(100) electrode and DESs on the atomic scale that hydrogen bond donor molecules and the surface crystallography of the electrode interface could significantly affect the arrangement of gold atoms of the electrode surface and chloride ions in the innermost Stern plane.

STM Study of the Initial Stage of Gold Intercalation of Graphene on Ir(111).

In this paper, we present a study of the sub-monolayer gold intercalation of graphene on Ir(111) using scanning tunnelling microscopy (STM). We found that Au islands grow following different kinetics than growth on Ir(111) without graphene. Graphene appears to increase the mobility of Au atoms by shifting the growth kinetics of Au islands from dendritic to a more compact shape. Graphene on top of intercalated gold exhibits a moiré superstructure, with parameters significantly different from graphene on Au(111) but almost identical to graphene on Ir(111). The intercalated Au monolayer shows a quasi-herringbone reconstruction with similar structural parameters as on Au(111).

Diffusion-controlled bridging of the Au Island and Au core in Au@Rh(OH)3 core-shell structure.

Hybrid nanostructures have garnered considerable interest because of their fascinating properties owing to the hybridization of materials and their structural varieties. In this study, we report the synthesis of [Au@Rh(OH)3]-Au island heterostructures using a seed-mediated sequential growth method. Through the thiol ligand-mediated interfacial energy, Au@Rh(OH)3 core-shell structures with varying shell thicknesses were successfully obtained. On these Au@Rh(OH)3 core-shell seeds, by modulating the diffusion of HAuCl4 in the porous Rh(OH)3 shell, site-specific growth of Au islands on the inner Au core or on the surface of the outer Rh(OH)3 shell was successfully achieved. Consequently, two types of distinct structures, the Au island-on-[Au@Rh(OH)3] dimer and Au island-Au bridge-[Au@Rh(OH)3] dumbbell structures with thin necks were obtained. Further modulations of the growth kinetics led to the formation of Au plate-Au bridge-[Au@Rh(OH)3] heterostructures with larger structural anisotropy. The flexible structural variations were demonstrated to be an effective means of modulating the plasmonic properties; the Au-Au heterostructures exhibited tunable localized surface plasmon resonance in the visible-near-infrared spectral region and can be used as surface-enhanced Raman scattering (SERS) substrates capable of emitting strong SERS signals. This diffusion-controlled growth of Au bridges in the Rh(OH)3 shells (penetrating growth) is an interesting new approach for structural control, which enriches the tool box for colloidal nanosynthesis. This advancement in structural control is expected to create new approaches for colloidal synthesis of sophisticated nanomaterials, and eventually enable their extensive applications in various fields.

Atomic-scale characterization of contact interfaces between thermally self-assembled Au islands and few-layer MoS2 surfaces on SiO2

The interaction between metallic nanoparticles and transition metal chalcogenides (TMDs) can realize new functionalities in thriving technologies such as optoelectronics and nanoengineering. Here we have investigated the self-assembly of triangular-shaped crystalline Au nanoislands on MoS2 flakes mechanically exfoliated or grown by chemical vapor deposition (CVD). The density and size of the islands are determined by substrate temperature, deposition flux, and subsurface morphology. The thickness of the MoS2 layers is measured by Raman spectroscopy, which also enables the evaluation of the strain and doping distributions induced by the Au islands. Top and cross-sectional images of the Au-MoS2 interface are obtained by scanning electron microscopy (SEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Sub-nanometer resolution of the Au, Mo and S layers reveals that the MoS2 flakes follow the corrugation of the SiO2 substrate, with flattening and wrinkling effects induced by the growth of the Au islands on top.

Criteria for electronic growth of Au on layered semiconductors

An electronic growth mode has been reported to occur in several noble metals on MoS2 but has not been observed on other layered semiconductors. In this work, the experiments show that Au(111) islands initially follow an electronic growth mode on WS2, matching the quantization seen in Au/MoS2. However, while epitaxial nanostructures with similar features are observed on WSe2, there is no sign of electronic growth. Binding energy calculations show that multiple bonding sites have nearly the same energy on both WS2 and MoS2, while Au strongly prefers a single bonding site on WSe2. Having multiple sites with the same energy gives flexibility in interfacial bonding that can alleviate strain from the 9+% lattice mismatch in these systems, which would, otherwise, easily suppress quantum size effects from electronic growth modes. These results should be useful in predicting which systems undergo quantized electronic growth on layered semiconductors.

Surfactant−free synthesis of flower−like Au NPs/Au island hybrid substrate for quantitative SERS detection of pesticide residues on fruit

Surface enhanced Raman scattering (SERS) has been extensively applied in the field of biochemical detection ascribed to its high sensitivity and nondestructive pattern. Nevertheless, the further improvement of such attractive protocol is severely hindered by the absence of enough surface roughness as well as the presence of organic surfactant. Herein, we demonstrated a highly sensitive and robust SERS hybrid substrate composed of plasmonic flower−like Au nanoparticles (FANPs)/Au island with clean surface. The development of this novel FANPs architecture could be attributed to the drastic reduction of Au 3+ ions, which triggered the overgrowth of Au atoms in the absence of surfactant. Meanwhile, the pre-existent Au monolayer on the silicon matrix were found to synchronously grew to Au islands, resulting in the formation of hybrid substrates. The FANPs/Au island hybrid substrate performed satisfactorily while monitoring 4 −mercaptobenzoic acid and gave out an excellent enhancement factor of 6.74 × 10 6 . Particularly, the high sensitivity makes the hybrid substrate a fascinating platform for practical monitoring. In this regard, the in−situ detection of thiabendazole on apple was conducted and a limit of detection low to 8.3 ng/mL was achieved. This high−performance SERS substrate provides more opportunities for appreciable in−situ assay in some practical fields. • A plasmonic flower−like Au NPs (FANPs)/Au island with clean surface was constructed without any surfactant. • An excellent enhancement factor as high as 6.74 × 10 6 was achieved by the FANPs/Au island hybrid substrate. • The in−situ detection of thiabendazole on apple was conducted and the limit of detection was achieved as low as 8.3 ng/mL.

Abstract A08: Diagnosis of breast implant associated anaplastic large cell lymphoma by analysis of cytokines in peri-implant effusions

Abstract Introduction: Breast implant associated anaplastic large cell lymphoma (BIA-ALCL) was recently recognized by the WHO as a lymphoma presenting a median of 8 years after insertion of breast implants for reconstructive surgery following breast cancer, for prophylactic mastectomy due to high genetic risk of breast cancer, e.g. BRACA1/2 mutations, or for other cosmetic reasons. The American Society of Plastic Surgeons BIA-ALCL Global Network reports there are 1,158 known cases of BIA-ALCL and 35 deaths across 46 countries worldwide as of January 28, 2022. Approximately 80% of Australian women present with a peri-implant effusion whereas in the USA, 30% present with a mass +/- lymphadenopathy. Five-year overall survival is 90.1% when disease is confined to a peri-implant effusion and capsule but 72.4% when disease extends beyond the capsule. Therefore, we set out to develop a diagnostic test for early disease detection in peri-implant effusions. Experimental procedure: Our initial publications from the USA and Italy revealed higher mean concentrations of IL-9, IL-10 and IL-13 in BIA-ALCL than in more common benign effusions due to capsule contracture, leakage, trauma and infection. To validate these findings in a larger number of patients, mostly from another geographic region (Australia), we evaluated cryopreserved peri-implant effusions of 25 patients with BIA-ALCL and 30 patients with benign seromas collected at Macquarie University Medical School in Sydney AU and Rhode Island Hospital in the USA. Informed consent and Institutional approvals were obtained. Cytokine concentrations were determined with the Biolegend Human Th Cytokine 12 plex multianalyte flow assay kit (Cat. No. 741028), San Diego, USA. Results: The results show that mean levels of IL-9, IL-10 and IL-13 were elevated 72-, 716- and 22-fold, respectively, in BIA-ALCL compared to benign effusions, and each cytokine separated the two groups with little overlap (P &amp;lt; 0.0001), Mann-Whitney test. For IL-10, there was 92% sensitivity, 100% specificity, Youden Index (YIA08_92), cut-off value 150pg/ml; for IL-9, 96% sensitivity, 80% specificity (YI=76) cut-off value 88pg/ml; for IL-13, 76% sensitivity, 96.7% specificity, (YI= 72.7) cut-off value 714pg/ml. Furthermore, the geometric mean of the 3 cytokines has an area under the Receiver Operated Curve (AUROC) value of 0.9947 with 100% sensitivity and 96% specificity (Youden index of 96). Only one other cytokine, IFNgamma, showed significant diagnostic value.Conclusions: Measurement of a panel of 12 cytokines representing different T helper subsets discriminates with high sensitivity and specificity peri-implant effusions of BIA-ALCL from benign peri-implant effusions, facilitating early diagnosis with potential for curative surgery. The consistent cytokine profile of IL-9, IL-10 and IL-13 in malignant peri-implant effusions in this and 2 previous studies of 40 patients across 3 continents suggest that a specific immune response to unique etiologic agent(s) is an early event in the pathogenesis of BIA-ALCL. Citation Format: Marshall E Kadin, Helen Hu, Elena Elena Shklovskaya, Anand Deva, Mark Dooner, Haiying Xu. Diagnosis of breast implant associated anaplastic large cell lymphoma by analysis of cytokines in peri-implant effusions [abstract]. In: Proceedings of the Third AACR International Meeting: Advances in Malignant Lymphoma: Maximizing the Basic-Translational Interface for Clinical Application; 2022 Jun 23-26; Boston, MA. Philadelphia (PA): AACR; Blood Cancer Discov 2022;3(5_Suppl):Abstract nr A08.

Electromigration of Au on Ge(111): Adatom and island dynamics

We have observed the motion of two-dimensional phases of Au on Ge(111) under an electric bias by in operando low energy electron microscopy. Electromigration of Au results in a complex dynamics that depends on the nature of the involved mobile phases: two-dimensional adatom gas or two-dimensional islands. We show that the Au adatoms move at the surface in the direction opposite to the electric current. The wind force induced by the electron flow is measured: the effective valence of Au (${Z}^{*}=\ensuremath{-}82\ifmmode\pm\else\textpm\fi{}15$) is directly deduced from the coverage profile of a Au adatom gas spatially retained by a strong Erlich-Schwoebel barrier at a downhill step edge. The velocity of two-dimensional Au islands versus island size reveals a mass transport by terrace diffusion inside the islands. The energy barrier for diffusion above 820 K is $1.16\ifmmode\pm\else\textpm\fi{}0.08$ eV and it strongly increases up to $3.1\ifmmode\pm\else\textpm\fi{}0.6$ eV below. We attribute this change of regime to a modification of diffusing species from single Au atoms at high temperature to Au clusters at low temperature. The strong shape fluctuations of the 2D islands is consistent with a nearly vanishing line tension of $1.2\ifmmode\pm\else\textpm\fi{}0.4$ meV/nm at 800 K.

Suspended Graphene Membranes to Control Au Nucleation and Growth.

Control of nucleation sites is an important goal in materials growth: nuclei in regular arrays may show emergent photonic or electronic behavior, and once the nuclei coalesce into thin films, the nucleation density influences parameters such as surface roughness, stress, and grain boundary structure. Tailoring substrate properties to control nucleation is therefore a powerful tool for designing functional thin films and nanomaterials. Here, we examine nucleation control for metals deposited on two-dimensional materials in a situation where substrate effects are absent and heterogeneous nucleation sites are minimized. Through quantification of faceted, epitaxial Au island nucleation on graphene, we show that ultralow nucleation densities with nuclei several micrometers apart can be achieved on suspended graphene under conditions where we measure 2-3 orders of magnitude higher nucleation density on the adjacent supported substrate. We estimate diffusion distances using nucleation theory and find a strong sensitivity of nucleation and diffusion to suspended graphene thickness. Finally, we discuss the role of surface roughness as the main factor determining nucleation density on clean free-standing graphene.

Low coverage disordered decanethiol monolayers on Au(001): A conjecture regarding the formation of Au-adatom-molecule complexes

We present a scanning tunneling microscopy study of decanethiol on Au(001) in the low coverage regime. As expected, the hex reconstruction is lifted, however, no ordered decanethiol phases form. We observe large areas free of Au islands and covered with a disordered decanethiol phase. I(t) spectroscopy measurements suggest that this disordered phase is dynamic and most likely comprises diffusing Au adatoms, decanethiol molecules, and/or Au-adatom-decanethiol molecule complexes. We have performed density functional theory calculations and show that the activation barrier for diffusion is lower when Au-adatom-molecule complexes are considered in comparison to the case of bare molecule. These findings suggest that although no vacancy pits form on Au(001), Au-adatoms expelled during the lifting of the hex reconstruction may be still important for the diffusion of thiol molecules on this surface.

Homoepitaxial overgrowth of (111) diamond films on Au-coated and Ni-coated substrates

Homoepitaxial growth of (111)-oriented diamond films on the Au-coated and Ni-coated diamond substrates by microwave plasma chemical vapor deposition (CVD) has been investigated. The process is involved with overgrowth of CVD diamond on Au and Ni islands formed by hydrogen plasma annealing of the 20 nm Au and Ni film coatings on diamond substrates. Cross-sectional transmission electron microscopy (TEM) observations show that both of the Au and Ni islands as single crystallites are in epitaxy with diamond substrate and no diamond growth occurs on top of those islands in the early stage of diamond deposition. The overgrowth of diamond over the metal islands results in excellent coalescence to form a continuous film with a lower defect density than the film without the metal coating. With such Au and Ni islands, the film stress can be further relaxed as shown with Raman spectroscopy.

3D hotspot matrix of Au nanoparticles on Au island film with a spacer layer of dithiol molecules for highly sensitive surface-enhanced Raman spectroscopy

Engineering of efficient plasmonic hotspots has been receiving great attention to enhance the sensitivity of surface-enhanced Raman scattering (SERS). In the present study, we propose a highly sensitive SERS platform based on Au nanoparticles (AuNPs) on Au island film (AuIF) with a spacer layer of 1,4-benzenedimethanethiol (BDMT). The three-dimensional (3D) hotspot matrix has been rationally designed based on the idea of employing 3D hotspots with a vertical nanogap between AuIF and AuNPs after generating large area two-dimensional hotspots of AuIF. AuNPs@BDMT@AuIF are fabricated by functionalizing BDMT on AuIF and then immobilizing AuNPs. The SERS performance is investigated with Rhodamine 6G as a probe molecule and the determined enhancement factor is 1.3 × 105. The AuNPs@BDMT@AuIF are then employed to detect thiram, which is used as a fungicide, with a detection limit of 13 nM. Our proposed platform thus shows significant potential for use in highly sensitive SERS sensors.

Ion-beam-induced structure fragmentation and dewetting in Au/Ti films

We investigate the formation of Au structures by continuing fragmentation of a Au film separated from Si (100) substrate by a Ti adhesion layer. The ion-beam processing uses 2 keV Cs+ projectiles. It induces the formation of a large variety of structures with dimensions from tens of microns down to a few nanometers, and shapes that include flat Au islands and clusters of Au nanoparticles. We identify different fragmentation mechanisms. In one pathway, Au structures are formed as pinch-off droplets detached from large Au islands undergoing solid-state dewetting. In a second pathway, a continuing cracking fragmentation produces Au structures with a wide range of sizes and shows self-similarity, expressed in a power law for volume distribution of fragments Vα with α = −2.03 ± 0.05. The measured α value is consistent with theoretical results in the literature modeling strong impact fragmentation. In the last stage of fragmentation evolution, Au nanostructures are spread over a texturized Si background. They assume shapes close to hemispherical, reflecting the increasing relevance of surface tension as dimensions decrease.

Properties of Au film on Ru(0001) revealed by AES, LEED, and DEPES

In this work the application of the surface sensitive experimental methods such as Auger electron spectroscopy, low energy electron diffraction, and directional elastic peak electron spectroscopy is shown to characterize the growth mode, the long and short range order of Au layers on the Ru(0001) surface. The adsorption was carried out at different substrate temperatures from room temperature till 460 °C. Auger signal from the substrate and the adsorbate recorded during the continuous Au adsorption indicates the formation of the first and then the second gold wetting layer at elevated substrate temperatures. At room temperature the formation of the second layer just before the completion of the first monolayer occurs. Further adsorption leads to the growth of three dimensional gold islands on 2 ML of Au on Ru(0001). At elevated temperatures the reduction of the Auger signal drop rate from the substrate and the signal rise rate from the adsorbate after the formation of 2 ML of Au can be rationalized by the coalescence of three dimensional Au islands and/or the decrease of the sticking coefficient of gold. Above 460 °C the saturation of Auger signals corresponding to 2 ML of Au is observed. The LEED pattern observations reveal the long range order within the clean and covered by about 5 ML of gold Ru(0001). The diffraction spots of the adsorbate reflect the Au(111) arrangement. The application of the DEPES method to the clean and covered by gold Ru(0001) surface reveals the presence of A and B type terraces on the Ru(0001) surface, as well as mutually rotated by 180° adsorbate domains, which exhibit the 12¯1111Au//01¯100001Ru and 1¯21¯111Au//01¯100001Ru orientations with respect to the crystalline substrate. The detailed R-factor analysis of experimental and theoretical DEPES distributions, the latter obtained with the use of the multiple scattering calculations, reveals equal population of A and B type Ru(0001) terraces, as well as unrotated and rotated Au(111) domains, which results in the six-fold symmetry DEPES intensity distributions for clean and covered substrate. The discussion of DEPES results concerns the adsorbate and substrate structures, inelastic mean free paths, and scattering properties of individual Au and Ru atoms described by the scattering factors and differential scattering cross sections.