Uniform Islands Research Articles

Machine learning to identify structural motifs in asphaltenes

Asphaltenes are organic compounds that aggregate in crude oil with two dominant molecular architectures: archipelago and continental. Continental architectures possess a single uniform island structure composed of aromatic rings in contrast to archipelago architectures with aromatic cores interconnected through aliphatic chains. The structural composition of asphaltenes varies globally due to geographical differences, posing challenges in their classification due to a lack of uniformity. This study is the first known exploration of using image-based supervised machine learning, particularly the ResNet-50 neural network, for the binary classification of asphaltenes into continental and archipelago motifs. 255 continental and archipelago models underwent structural augmentations to create a sample size of 1,530 asphaltene structures that is robust enough for accurate results in both the training and testing portions of the machine learning. These augmentations included the repeated addition of carbons until a complete pentane chain was added to a specified carbon on each asphaltene structure. Using Mathematica, supervised ResNet-50 image-based classification was used on both original and augmented structure datasets to classify as either archipelago or continental. The classification was also implemented using topological similarity searching for association between atoms and the distance between them for further molecule identification. This study demonstrates the surprising effectiveness of image-based classification compared to traditional topological feature-based methods. Our results reveal that deep learning techniques, especially image-based approaches, provide novel and insightful ways to differentiate complex molecular structures like asphaltenes, challenging the traditional reliance on topological features alone. This research opens new avenues in chemical analysis and molecular characterization, highlighting the potential of machine learning in complex molecular systems.

Improving MgO/Fe insulator-metal interface structure through oxygen-precoating of Fe(0 0 1)

We grew atomically flat and electronically uniform MgO island terraces on a Fe(001) whisker substrate precoated by a p(1 × 1) oxygen monolayer film. This interface engineering process increased about 10 times the size of MgO islands compared to the size of MgO islands directly grown on Fe(001), showing that the interface oxygen monolayer plays an essential role in MgO growth. Importantly, each squared-shape atomically flat MgO island includes only a few atomic defects, which provides high-quality insulating layers. Further, the MgO islands have an electronic decoupling functionality from the metal substrate. Surface morphology and local electronic structures were studied using a home-built ultrahigh vacuum scanning tunneling microscopy (STM) at a temperature of 5 K.

Midchannel islands in lowland river corridors and their impacts on flow structure and morphology:A numerical based conceptual analysis

Midchannel islands (MCIs) are influential geomorphic units in regulating morphological and ecological dynamics in sand-dominated rivers. The primary objectives of the study were to understand a) the relationship between morphometric characteristics of the basin and the occurrence location of the MCIs, b) the role of MCIs on the hydraulic gradient and the other hydraulic variables along the reach, and c) the influence of island growth process on hydrodynamics in the wake and contraction regions. Spatial distributions of MCIs depending on the morphometric features of the three characteristic basins were considered. While the basin-scale analysis was conducted using GIS-based data, the reach and individual scale analyses were performed based on a Reynolds-averaged Navier–Stokes (RANS) model. Uniform circular cylinder and island geometries were exposed to identical flow conditions. The expansion of these island geometries was mimicked both in rectangular and trapezoidal cross-sections. The variation of water surface slope and bottom shear stress variables, which greatly trigger the intensive bilateral interaction between hydrological-morphological-ecological elements in river corridors, depending on the growth of the island, was determined. The role of imposed island geometry on the secondary flow structure within the downstream cross-section of the island and streamwise velocity fluctuations in contraction regions were analyzed. The basin-scale analysis showed that with decreasing basin slopes, the family of islands emerged at a longer distance to the basin outlet. It was also seen that MCIs location is closer to the basin outlet forbasins with a lower aspect ratio. Besides, asymmetrical large-scale counter-rotating streamwise vortices were detected behind the MCIs based on numerical simulations. GIS-based data showed that this coherent flow structure brought about channel adjustments in downstream of the island. In addition to morphological consequences, it was hypothesized that this alteration in the flow structure due to MCI has potential impacts on riverine ecology. These impacts are increase in groundwater recharge, vertical exchange of surface–subsurface water, local heterogeneity in sediment characteristics (i.e., convenient fish spawning areas), and enlargement in the hyporheic zone.

Definitely Islands? Experimental investigation of definite islands

Experimental work on islands has used formal acceptability judgment studies to quantify the severity of different island violations. This current study uses this approach to probe the (in-)violability of definite islands, an understudied island, in offline and online measures. We conducted two acceptability judgment studies and find a modest island effect. However, rating distributions appear bimodal across definites and indefinites. We also conducted a self-paced reading experiment, but found no sig- nificant effects. Overall, offline, definite islands differ from other uniform islands, but online, the results are more complicated.

Rational construction of Au–Ag bimetallic island-shaped nanoplates for electrocatalysis

Active electrocatalysts are the key to water splitting for hydrogen production through the electrolysis. In this paper, 50 nm silver nanoplates were used as templates for synthesis of Au–Ag island-shaped nanoplates by controlling the surface chemistry. The guiding mechanism of polyvinylpyrrolidone (PVP, Mw = 40 000) to Au–Ag island-shaped nanoplates crystal was also further investigated. It is found that the surface energy of Ag nanoplates between (100) and (111) crystal planes can be regulated by varying the amount of PVP in the system. Then a uniform Au-Ag triangular island nanostructure was obtained. Compared with the Ag nanoplates catalysts, the Au–Ag island nanoplates catalysts show the superior catalytic performances in hydrogen evolution electrocatalysis (HER). These results demonstrate a new surface chemistry modification by PVP and a galvanic displacement reaction for designing the active electrocatalysts. More importantly, the Au–Ag island-shaped nanoplates show an unconventional growth mode of preserving the original Ag nano-triangular crystal structure. The enhanced performance in electrocatalysis can be mainly attributed to Au–Ag alloy structure, which allows the appearance of synergistic effects. The present work demonstrates the crucial roles of surface chemistry in catalysts synthesis, which may guide the design of active bimetallic catalysts.

On the Island Sensitivity of Topicalization in Norwegian: An Experimental Investigation

Mainland Scandinavian languages have been reported to allow movement from embedded questions, relative clauses, and complex NPs—domains commonly considered to be islands crosslinguistically. Yet in formal acceptability studies Scandinavian participants often show ‘island effects’: they reject island-violating movement similarly to native speakers of ‘island-sensitive’ languages. To investigate this apparent mismatch between informal and formal judgments, we conducted two acceptability judgment experiments testing the acceptability of topicalization from various island domains in Norwegian. We were interested in determining whether we could (i) find evidence for island insensitivity and (ii) pin down the source of qualitatively different island effects. We asked whether such effects are best explained as reflecting violations of a uniform syntactic constraint or extrasyntactic factors. Our results suggest that embedded questions and relative clauses are not uniform syntactic islands for topicalization, but complex NPs are. Unexpectedly, we also found evidence suggesting that conditional adjunct clauses may not be islands.

(Invited) Fabrication Technique for Low-Temperature Aqueous Solution-Processed Oxide Thin-Film Transistors

Thin-film transistors (TFTs) prepared using oxide semiconductors have attracted considerable attention for use in driving devices owing to their excellent electrical properties (1). Alternative facile fabrication methods based on solution processing are recognized as advanced oxide TFT fabrication methods (2, 3). Solution-process fabrication is promising technology owing to advantages such as lower processing costs, easier large-area fabrication, and higher throughput compared to conventional vacuum processing. However, it has several limitations that must be mitigated so that the method can be used in practical applications. One such limitation is the processing temperature for the fabrication of solution-processed oxide TFTs. In general, solution-processed oxide TFTs need relatively high-temperature annealing for metal–oxide–metal bond formation and decomposition of the solvents and ligands of metal salts. High-temperature annealing over 400 °C cannot incorporate onto the flexible substrate. Another limitation is that the fabrication process is complex. Although solution processing can be performed using basic equipment such as a coater and annealing equipment, it requires a complicated photolithography process for device integration. A simple fabrication process based on direct patterning procedures is useful for maximizing the advantages of solution processing. In this presentation, we introduce our recent studies on techniques for fabricating low-temperature aqueous solution-processed oxide TFTs, as well as simpler fabrication based on the direct patterning process. We demonstrate the improvement in the characteristics of low-temperature oxide TFTs by applying the hydrogen injection and oxidation (HIO) process (4). From the technical standpoint, decomposing residual species efficiently is of primary importance. We initiated the reduction reaction by hydrogen injection for decomposing the residual spices. The characteristics of the resulting In-Ga-Zn oxide (IGZO)-based TFTs were evaluated by applying the HIO method at low temperatures. The fabrication of IGZO TFTs on film substrate were also demonstrated. For process simplification, we report a direct photoreactive patterning method for fabricating solution-processed IGZO TFTs using a simple aqueous IGZO precursor without any the need for organic-based additives. This is accomplished by photo-oxidation of water molecules based on free radical reactions induced by short-wavelength UV light. In addition, a soft etching step using a dilute organic acid is employed. By combining these processes, a photoreactive patterning system capable of generating uniform island shapes for fabricating solution-processed IGZO TFTs is demonstrated. We demonstrate the advantages of the TFTs fabricated using the direct patterning process by comparing their performance with that of the TFTs fabricated using the conventional photolithography process. K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano, and H. Hosono, Nature, 432, 488 (2004). E. Fortunato, P. Barquinha, and R. Martins, Adv Mater, 24, 2945 (2012). S. J. Kim, S. Yoon, and H. J. Kim, Japn J Appl Phys, 53 (2014). M. Miyakawa, M. Nakata, H. Tsuji, Y. Fujisaki, and T. Yamamoto, AIP Advances, 6 (2016).

A phase field crystal model simulation of morphology evolution and misfit dislocation generation in nanoheteroepitaxy

A phase field crystal (PFC) model is employed to study morphology evolution of nanoheteroepitaxy and misfit dislocation generation when applied with enhanced supercooling, lattice mismatch and substrate vicinal angle conditions. Misfit strain that rises due to lattice mismatch causes rough surfaces or misfit dislocations, deteriorates film properties, hence, efforts taken to reveal their microscopic mechanism are significant for film quality improvement. Uniform islands, instead of misfit dislocations, are developed in subcritical thickness film, serving as a way of strain relief by surface mechanism. Misfit dislocations generate when strain relief by surface mechanism is deficient in higher supercooling, multilayers of misfit dislocations dominate, but the number of layers reduces gradually when the supercooling is further enhanced. Rough surfaces like islands or cuspate pits are developed which is ascribed to lattice mismatch, multilayers of misfit dislocations generate to further enhance lattice mismatch. Layers of misfit dislocations generate at a thickening position at enhanced substrate vicinal angle, this further enhancing the angle leading to sporadic generation of misfit dislocations.

Structure of heterosystems formed by a SnO2 film and island metal (Ag, Au, or Pd) condensate

We have studied the phase composition and microstructure of thin tin(IV) oxide films surfacemodified with silver, gold, and palladium nanoislands. Using high-energy electron diffraction, we have shown for the first time that the thermal oxidation of the Sn films leads to the formation of nanocrystalline multiphase SnO2 films in which the major phase is orthorhombic. Also present are (in order of decreasing content) tetragonal and cubic phases. Blocks of SnO2(O) subgrains with 〈101〉 texture contain dislocations and stacking faults, which are interpreted as layers of the tetragonal phase. It has been shown that vacuum condensation makes it possible to modify the surface of SnO2 films with noble metals and obtain homogeneous nanoisland coatings characterized by a unimodal, uniform island size distribution.

Structure and optical properties of polycrystalline NiO films and its resistive switching behavior in Au/NiO/Pt structures

Structure and optical of polycrystalline NiO films fabricated by reactive sputtering and its resistive switching properties in Au/NiO/Pt structures are investigated. The size of surface uniform pyramid-like islands and average surface roughness increase with the increase of NiO film thickness (t). The NiO films grow with the preferred (111) orientation at 400°C, but both (100) and (110)-oriented grains exist in the films fabricated at room temperature. Raman results reveal that the crystallinity of the films fabricated at 400°C becomes good by comparing with that at room temperature. The optical band gap monotonically decreases from 4.44eV at t=22nm to 3.55eV at t=800nm. The resistance of the Au/NiO/Pt/Ti/glass structures could be switched between two stable states including low and high resistance states. The bipolar endurance performance of the resistive switching remains nondegradable after 200 cycles. The resistive switching can be ascribed to the carrier trapping and detrapping induced by the electric field, which can change the thickness of the depletion layer at Au/NiO interface.

Thin film properties of tetracyanoquinodimethane (TCNQ) with novel templating effects

Film properties and new templating behaviours in strong electron acceptor TCNQ.

Utility of island populations in re-introduction programmes--relationships between Arabian gazelles (Gazella arabica) from the Farasan Archipelago and endangered mainland populations.

Understanding local adaptation and population differentiation is vital to the success of re-introduction initiatives. As other mammals living on islands, Arabian gazelles (G. arabica) show reduced body size on the Farasan archipelago, which we corroborated in this study through morphometric analyses of skulls. In the light of the steep population decline on the Arabian Peninsula – but stable population development on the archipelago – we tested the potential suitability of Farasan gazelles as a source for re-introductions on the mainland. We therefore investigated genetic differentiation between Farasan and mainland populations using eleven nuclear microsatellite loci and detected a distinct genetic cluster exclusively present on the archipelago, which we inferred to be separated from the mainland cluster for less than 2000 years. About 30% of sampled individuals from Farasan Islands showed assignment to a mainland cluster with signs of ongoing introgression. Analyses using the isolation-with-migration model confirmed recent (probably human-induced) bidirectional exchange of gazelles between mainland and island populations. Hence, the surprisingly uniform island dwarfism most likely reflects phenotypic plasticity, that is, altered morphology as a direct consequence of harsh environmental conditions and resource limitation on the archipelago. Should a further decline of Arabian gazelles on the mainland necessitate restocking in the future, Farasan gazelles may thus become an additional source for captive breeding programmes.

Evolution and coarsening of Si-rich SiGe islands epitaxially grown at high temperatures on Si(0 0 1)

In this work we investigate by means of atomic force microscopy in combination with selective wet etching experiments coalescence and coarsening effects on the morphology evolution of Si-rich SiGe quantum dots and islands grown epitaxially at high temperatures on Si(001) substrates. We demonstrate that under certain growth conditions remarkably uniform island size distributions can be achieved for dome and cupola islands, while the morphological transition is dominated by coarsening and coalescence effects similar to Ostwald ripening. Under further deposition the uniformly sized cupola islands transform into larger islands with even steeper side facets (>80°). The footprints obtained from selective wet etching experiments performed on the merging islands reveal that basically all atoms of the two islands are involved in the coarsening process.

Origins of saccharin-induced stress reduction based on observed fracture behavior of electrodeposited Ni films

This research presents experimental results of an investigation aimed at understanding grain size driven mechanical processes in electrodeposited Ni thin films where saccharine additions are commonly used to improve mechanical properties. Ni films were fabricated using salfamate-based electro chemical baths, where it is empirically known that mmol/l concentrations of saccharine will reduce the observed tensile stress in addition to lowering the grain size up to a few nanometer scales. Some previous observations and several theoretical models suggest that saccharine incorporation results in sulfur segregation at grain boundaries. Since grain boundary formation is also associated with tensile stress evolution, a plausible hypothesis is that saccharine additions are directly altering grain boundary energetics. This suggests that saccharine additions should also have an observable effect on intergranular fracture in these films. To test this prediction, in situ stress measurements during film growth and fracture testing of these same films were compared. Lithographically patterned substrates were used to produce films with ordered arrays of uniform islands, which demonstrated island size effects on stress evolution, and enabled a well-defined notch geometry along one of the island boundaries to facilitate fracture experiments. In situ uniaxial tensile testing under in a scanning electron microscope was then used to obtain the fracture strength of such specimens. This technique provided real time recording of microscopic deformation during uniaxial tensile loading. The observed relationships among residual stress, grain size, and fracture strength were then analyzed with detailed models of both film growth and fracture.

Characterisation and electrocatalytic activity of PtNi alloys on Pt{1 1 1} electrodes formed using different thermal treatments

The preparation of two different types of PtNi overlayer supported on Pt{111} together with their characterisation by cyclic voltammetry (CV), scanning tunnelling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) is reported. The first PtNi surface was created by resistively heating to approximately 1100K a 10–2M droplet of aqueous nickel (II) chloride solution attached to a Pt{111} Clavilier bead electrode in the nitrogen/water atmosphere of the electrochemical cell. From STM, it was evident that the crystal surface was covered with small, closely packed and uniform islands visible over the whole surface. XPS data indicated that although platinum was still present in its metallic state, the surface of the islands consisted largely of a Ni oxide/hydroxide phase. Subsequent electrocatalytic analysis showed that this oxidised PtNi surface exhibited lower activity than pure platinum towards the oxygen reduction reaction (ORR). The second PtNi surface was formed by subsequently flame annealing the Ni oxide/hydroxide adlayer to approximately 900K outside of the electrochemical cell and cooling the electrode rapidly in a stream of hydrogen. STM showed that again, small islands had formed which, according to XPS, corresponded to a metallic PtNi phase. However, the surface produced was flatter than before with clear terrace structures also being observed. This behaviour overall would be consistent with preferential segregation of either Pt or Ni (oxide/hydroxide) from a PtNi alloy depending on the oxidising nature of the ambient after annealing and cooling as reported previously by Kibler for PtRu alloys. By controlling the number of flame annealing treatments, CV revealed a gradual diminution in the amount of nickel present at the selvedge. The reduced, hydrogen cooled platinum-rich PtNi phase exhibited a current density for ORR ten times higher than that of Pt{111} (as measured by the current density in mA/cm2 at 0.9V) and a positive shift in the value of E1/2 by approximately 70mV.

Fabrication and characteristics of self-assembly nano-polystyrene films by laser induced CVD

The self-assembly nano-polystyrene (PS) films have been prepared by laser induced CVD at room temperature. The XPS, Raman and UV–vis absorption spectra all indicated that the films were PS. The optical properties, microstructure and controllable nanostructure of PS films have been investigated. Dewetting-like microstructure in PS films was investigated and uniform island structures with a diameter of about 200nm were observed at the deposition pressure of 14Pa. The films possess good toughness and precisely controlled thicknesses. The free-standing PS films with thickness of 10nm could be obtained by this method though a series of process.

Strategies for the Immobilization of Bacteriophages on Gold Surfaces Monitored by Surface Plasmon Resonance and Surface Morphology

The use of bacteriophages as recognition elements for biosensing techniques has recently provoked much interest. Surface plasmon resonance, scanning electron microscopy, and atomic force microscopy were used for the real-time monitoring of the attachment of methicillin-resistant Staphylococcus aureus (MRSA) bacteriophages to gold using several immobilization methods. The MRSA bacterial capture efficiency of phage-functionalized surfaces was studied. We found that whereas the physisorption of phages to gold surfaces affects their biofunctionality, as expressed by their lysing efficiency of bacteria, phages bound via mixed self-assembled monolayers of l-cysteine and 11-mercaptoundecanoic acid permitted both the recognition and disruption of bacterial membranes. This is due to the formation of uniform islands on the gold surfaces, permitting an oriented positioning of the phages, thus better exposing their recognition proteins.

Late Oligocene to Middle Miocene rifting and synextensional magmatism in the southwestern Sierra Madre Occidental, Mexico: The beginning of the Gulf of California rift

Although Basin and Range–style extension affected large areas of western Mexico after the Late Eocene, most consider that extension in the Gulf of California region began as subduction waned and ended ca. 14–12.5 Ma. A general consensus also exists in considering Early and Middle Miocene volcanism of the Sierra Madre Occidental and Comondú Group as subduction related, whereas volcanism after ca. 12.5 Ma is extension related. Here we present a new regional geologic study of the eastern Gulf of California margin in the states of Nayarit and Sinaloa, Mexico, backed by 43 new Ar-Ar and U-Pb mineral ages, and geochemical data that document an earlier widespread phase of extension. This extension across the southern and central Gulf Extensional Province began between Late Oligocene and Early Miocene time, but was focused in the region of the future Gulf of California in the Middle Miocene. Late Oligocene to Early Miocene rocks across northern Nayarit and southern Sinaloa were affected by major approximately north-south– to north-northwest–striking normal faults prior to ca. 21 Ma. Between ca. 21 and 11 Ma, a system of north-northwest–south-southeast high-angle extensional faults continued extending the southwestern side of the Sierra Madre Occidental. Rhyolitic domes, shallow intrusive bodies, and lesser basalts were emplaced along this extensional belt at 20–17 Ma. Rhyolitic rocks, in particular the domes and lavas, often show strong antecrystic inheritance but only a few Mesozoic or older xenocrysts, suggesting silicic magma generation in the mid-upper crust triggered by an extension-induced basaltic influx. In northern Sinaloa, large grabens were occupied by huge volcanic dome complexes ca. 21–17 Ma and filled by continental sediments with interlayered basalts dated as 15–14 Ma, a stratigraphy and timing very similar to those found in central Sonora (northeastern Gulf of California margin). Early to Middle Miocene volcanism occurred thus in rift basins, and was likely associated with decompression melting of upper mantle (inducing crustal partial melting) rather than with fluxing by fluids from the young and slow subducting microplates. Along the eastern side of the Gulf of California coast, from Farallón de San Ignacio island offshore Los Mochis, Sinaloa, to San Blas, Nayarit, a strike distance of >700 km, flat-lying basaltic lavas dated as ca. 11.5–10 Ma are exposed just above the present sea level. Here crustal thickness is almost half that in the unextended core of the adjacent Sierra Madre Occidental, implying significant lithosphere stretching before ca. 11 Ma. This mafic pulse, with subdued Nb-Ta negative spikes, may be related to the detachment of the lower part of the subducted slab, allowing an upward asthenospheric flow into an upper mantle previously modified by fluid fluxes related to past subduction. Widespread eruption of very uniform oceanic island basalt–like lavas occurred by the late Pliocene and Pleistocene, only 20 m.y. after the onset of rifting and ∼9 m.y. after the end of subduction, implying that preexisting subduction-modified mantle had now become isolated from melt source regions. Our study shows that rifting across the southern-central Gulf Extensional Province began much earlier than the Late Miocene and provided a fundamental control on the style and composition of volcanism from at least 30 Ma. We envision a sustained period of lithospheric stretching and magmatism during which the pace and breadth of extension changed ca. 20–18 Ma to be narrower, and again after ca. 12.5 Ma, when the kinematics of rifting became more oblique.

Alongshore variation in the morphology of coastal dunes: Implications for storm response

The geomorphological impact of an extreme storm on a barrier island tends to be modeled using a single cross-shore transect and dependent only on the elevation of the storm surge relative to the height of the dune. The foredune line, however, is rarely uniform and can exhibit considerable variation in height and width alongshore at a range of length scales. The purpose of this modeling study is to determine how alongshore variations in dune height affect barrier island response to extreme storms. The MIKE21 wave and current model is used to predict the morphological response of Matagorda Peninsula, Texas in response to storm surges associated with dune scarping, washover and inundation. The extent and degree of dune-scarping, washover and shoreline erosion is predicted for each storm scenario, with respect to the base morphology of the island and low-pass filtered forms in which small-scale topographic variance is removed. Results suggest that small variations in the height of an otherwise alongshore uniform foredune act as overwash conduits and are unstable, leading to a more variable duneline that is more susceptible to change by subsequent storms. The vertical development of the washover gaps in the duneline is limited and eventually replaced by a lateral expansion that erodes adjacent dunes and leads to a more uniform island elevation. The loss of island elevation is greater for the (original) unfiltered alongshore profile, but relatively uniform duneline is the most unstable and exhibits the greatest morphological change. The different alongshore profile responses suggest that the impact of an extreme storm is sensitive to initial conditions and specifically the pre-storm variability of the crest elevation alongshore. This in turn suggests that the evolution of barrier islands is dependent on storm history until the variability in the duneline elevation reaches a maximum. Further study of barrier island response to storm sequencing with and without post-storm recovery, however, is required to understand the evolution and form for the prototype island.

Lead growth on Si(111) surfaces reconstructed by indium

We study the Pb growth on both √3 × √3-In and 4 × 1-In reconstructed Si(111) surfaces at room and low temperature (160 K). The study takes place with complementary techniques, to investigate the role of the substrate reconstruction and temperature in determining the growth mode of Pb. Specifically, we focus on the correlation between the growth morphology and the electronic structure of the Pb films. The information is obtained by using Auger electron spectroscopy, low energy electron diffraction, soft x-ray photoelectron spectroscopy, scanning tunneling microscopy and spot profile analysis–low energy electron diffraction. The results show that, at low temperature and coverage ≤12 ML on the Si(111)√3 × √3–In surface, Pb does not alter the initial semiconducting character of the substrate and three-dimensional Pb islands with poor crystallinity are grown on a wetting layer. On the other hand, for the same coverage range, Pb growth on the Si(111)4 × 1–In surface results in metallic Pb(111) crystalline islands after the completion of a double incomplete wetting layer. In addition, the bond arrangement of the adatoms is studied, confirming that In adatoms interact more strongly with the silicon substrate than the Pb ones. This promotes a stronger Pb–Pb interaction and enhances metallization. The onset of the metallization is correlated with the amount of pre-deposited In on the Si(111) surface. The decoupling of the Pb film from the 4 × 1-In interface can also explain the unusual thermal stability of the uniform height islands observed on this interface. The formation of these Pb islands is driven by quantum size effects. Finally, the different results of Pb growth on the two reconstructed surfaces confirm the importance of the interface, and also that the growth morphology, as well as the electronic structure of the Pb film can be tuned with the initial substrate reconstruction.