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Magnetostrictive thin films, exhibit significant utility as functionalization materials for Surface acoustic wave sensors designed for magnetic field measurements. This research investigates the influence of annealing under vacuum and magnetic field at various temperatures on the magnetic properties of the FeCo/TbCo2 thin film and therefore on the sensitivity of shear and Rayleigh acoustic waveguides functionalized with these magnetic layers. The observed effects include a reduction in magnetic anisotropy field and an increase in magnetostriction. XPS and TEM coupled with EDS microanalysis provide insights into the variations in the properties of the nanostructured magnetic film. To safeguard the magnetic film, a thin layer of SiO2 is deposited on top, serving as a protective shield. The inclusion of this layer amplifies sensitivity to applied magnetic fields for modes with shear polarization while reducing sensitivity for Rayleigh mode. In ST‐cut Quartz, the shear waves become waveguided upon the incorporation of magnetic thin films, with further enhancement achieved by introducing a SiO2 layer. Rayleigh waves are evanescent modes, the penetration depth is in the order of wavelength, and the addition of SiO2 decrease the wave confinement and therefore the sensitivity. The findings are supported by a theoretical model and experimentally validated results. [ABSTRACT FROM AUTHOR]

Data recently obtained on model FeCrNi(Mo), 316 L stainless steel, and FeCrNiCo(Mo) passivated surfaces by advanced surface analysis and density functional theory modeling are comprehensively discussed to unravel the multiple effects that molybdenum might have at the nanometer and atomic scales to enhance the stability of passive films. The key role played on corrosion protection by the compositional and structural nanoscale defects of the passive film that originate from the pre-passivation mechanisms of the surface is considered. It is shown how Mo, enriched together with Cr in the nanometer-thick passive film, can combine several effects to enhance the resistance to Cl--induced passivity breakdown. Enriched as Mo(VI) species in the outer exchange layer of the passive film, Mo impedes the deep penetration of Cl- ions and limits their access to the inner barrier layer. Dispersed as Mo(IV) at the interface with the inner layer, Mo protects against the entry of Cl- ions into the defect sites of the Cr(III) oxide barrier. Present as Mo(IV + δ) in the Fe-rich compositional nanoscale defects self-generated by the local failure of Cr supply upon initial formation of the barrier layer, Mo enhances the selective dissolution of iron and its replacement by chromium and molybdenum. By impeding the formation of O vacancies, Mo also increases the resistance against chloride entry in the oxide matrix, thereby curing these the Fe-rich weak sites against Cl--induced passivity breakdown. [ABSTRACT FROM AUTHOR]

Surface spectroscopy analysis and electrochemistry were applied to study the effects of surface preparation by vibratory polishing on the passivity of stainless steel 304L surfaces. Compared to grinding by traditional mechanical polishing, vibratory polishing promotes the enrichment of Cr(III) oxide and hydroxide species in the duplex chemical structure of the surface native oxide film by enhancing selective Fe oxidation and dissolution. As a result, spontaneous passivity, tested in aggressive sulphuric acid electrolyte, is enhanced. However, in the absence of enrichment in Mo(IV) and Mo(VI) species in the passive film, the Cr enrichment does not enhance passivity upon anodic polarisation nor increase the resistance to Cl-induced passivity breakdown and initiation of localised corrosion in accelerated testing conditions. The results provide comprehensive insight into the mechanisms underlying the passivity enhancement of stainless steel by surface engineering. [ABSTRACT FROM AUTHOR]

X‐ray photoelectron spectroscopy analysis was applied to investigate the thermal stability under ultra‐high vacuum environment of the surface oxide film formed by electrochemical passivation of a newly designed Cr15Fe10Co5Ni60Mo10 (at.%) multi‐principal element alloy and providing the alloy superior localized corrosion resistance compared to conventional stainless steels and alloys. A spectral decomposition methodology involving the subtraction of Auger peaks overlapping the Fe 2p and Co 2p core level regions was applied for quantification of the oxide film composition and thickness. The results show that, at 100°C, the passive oxide film is mainly dehydrated and dehydroxylated. Obvious loss of Ni hydroxide and conversion of Mo (VI) to Mo (IV) species are observed at 200°C, with further reduction of Mo species to Mo (III) observed at 300°C. In this temperature range, the total cation quantity in the oxide film remains stable despite the compositional alteration. At 400°C, Cr (III) oxide forms at the expense of Fe and Mo oxides, resulting in an oxide film essentially consisting of chromium oxide. At 500°C, Cr (III) oxide is eliminated, making the passive film unstable at this temperature. Possible Cr oxide removal mechanisms are discussed. [ABSTRACT FROM AUTHOR]

Inhibition of the initiation of intergranular corrosion was modeled at the atomic scale for 2-mercaptobenzothiazole (MBT) adsorbed on a (110)-oriented copper bi-crystal exposing an emergent Σ9 coincident site lattice (CSL) grain boundary (GB) using dispersion-corrected density functional theory (DFT-D). At both isolated molecule and full, dense monolayer coverages, the molecule adsorbed on the grain and GB sites stands perpendicular or tilted with no parallel orientation to the surface being favored. Chemical bonding of the thione and thiolate conformers involves both S atoms or the exocyclic S and N atoms, respectively. The full, dense monolayer is formed with a net gain in energy per surface area, but at the cost of a significant molecule deformation. It significantly enhances the Cu vacancy formation energy at the grain and GB sites, revealing that MBT also inhibits Cu dissolution for the more susceptible GBs with efficiency depending on atomic density of GB emergence. [ABSTRACT FROM AUTHOR]

Atomic devices such as atomic clocks and optically-pumped magnetometers rely on the interrogation of atoms contained in a cell whose inner content has to meet high standards of purity and accuracy. Glass-blowing techniques and craftsmanship have evolved over many decades to achieve such standards in macroscopic vapor cells. With the emergence of chip-scale atomic devices, the need for miniaturization and mass fabrication has led to the adoption of microfabrication techniques to make millimeter-scale vapor cells. However, many shortcomings remain and no process has been able to match the quality and versatility of glass-blown cells. Here, we introduce a novel approach to structure, fill and seal microfabricated vapor cells inspired from the century-old approach of glass-blowing, through opening and closing single-use zero-leak microfabricated valves. These valves are actuated exclusively by laser, and operate in the same way as the "make-seals" and "break-seals" found in the filling apparatus of traditional cells. Such structures are employed to fill cesium vapor cells at the wafer-level. The make-seal structure consists of a glass membrane that can be locally heated and deflected to seal a microchannel. The break-seal is obtained by breaching a silicon wall between cavities. This new approach allows adapting processes previously restricted to glass-blown cells. It can also be extended to vacuum microelectronics and vacuum-packaging of micro-electro-mechanical systems (MEMS) devices. [ABSTRACT FROM AUTHOR]

Investigating the interaction of organic inhibitors with metal and alloy surfaces is crucial for an atomic-scale understanding of their protection efficiency, particularly on the initiation of localized corrosion by pitting. Quantum chemical DFT calculations were performed to optimize the constructed model of a depassivated copper surface and to study the adsorption of 2-mercaptobenzothiazole (MBT), on different zones exposed by local depassivation. Reactive sites exist at the metal surface, at the oxide surface, as well as on the oxide edges and oxide walls. The surface-reactive sites are the unsaturated and saturated copper atoms and singly and doubly unsaturated oxygen atoms of the oxide, and the copper atoms of the metal. The sulfur (Sexo and Sendo) and nitrogen (N or NH) atoms are the reactive sites in the molecules. MBT can covalently bond to the oxide surface as well as to the oxide edges, oxide walls, and metal surface exposed by depassivation. For the thione species, local adsorption strength decreases as oxide edges > oxide surface > metal surface > oxide walls, suggesting that MBT heals the low coordinated sites. For the thiolate species, adsorption strength is similar on the different area, except the oxide walls. The results show the ability of the inhibitor to interact on different zones of a locally depassivated surface and to form a strongly adsorbed organic film, which can block the initiation of localized corrosion by enhancing the interfacial barrier properties, including in the local surface areas incompletely passivated or locally damaged by depassivation. [ABSTRACT FROM AUTHOR]

We report the realization and characterization using coherent population trapping (CPT) spectroscopy of an octadecyltrichlorosilane (OTS)-coated centimeter-scale Cs vapor cell. The dual-structure of the resonance lineshape, with presence of a narrow structure line at the top of a Doppler-broadened structure, is clearly observed. The linewidth of the narrow resonance is compared to the linewidth of an evacuated Cs cell and of a buffer gas Cs cell of similar size. The Cs-OTS adsorption energy is measured to be (0.42±0.03) eV, leading to a clock frequency shift rate of 2.7×10-9/K in fractional unit. A hyperfine population lifetime, T1, and a microwave coherence lifetime, T2, of 1.6 and 0.5ms are reported, corresponding to about 37 and 12 useful bounces, respectively. Atomic-motion induced Ramsey narrowing of dark resonances is observed in Cs-OTS cells by reducing the optical beam diameter. Ramsey CPT fringes are detected using a pulsed CPT interrogation scheme. Potential applications of the Cs-OTS cell to the development of a vapor cell atomic clock are discussed. [ABSTRACT FROM AUTHOR]

A model experimental approach, providing molecular scale insight into the build up mechanisms of a corrosion inhibiting interface, is reported. 2-mercaptobenzimidazole (2-MBI), a widely used organic inhibitor, was deposited from the vapor phase at ultra-low pressure on copper surfaces in chemically-controlled state, and X-ray photoelectron spectroscopy was used in situ to characterize the adsorption mechanisms upon formation of the inhibiting film. On copper surfaces prepared clean in the metallic state, the intact molecules lie flat at low exposure, with sulfur and both nitrogen atoms bonded to copper. A fraction of the molecules decomposes upon adsorption, leaving atomic sulfur on copper. At higher exposure, the molecules adsorb in a tilted position with sulfur and only one nitrogen bonded to copper, leading to a densification of 2-MBI in the monolayer. A bilayer is formed at saturation with the outer layer not bonded directly to copper. In the presence of a pre-adsorbed 2D oxide, oxygen is substituted and the molecules adsorb intactly without decomposition. A 3D oxide prevents the bonding of sulfur to copper. The molecular film formed on metallic and 2D oxide pre-covered surfaces partially desorbs and decomposes at temperature above 400 °C, leading to the adsorption of atomic sulfur on copper. [ABSTRACT FROM AUTHOR]

The demonstration of miniature atomic clocks (MACs) based on coherent population trapping (CPT) with improved mid- and long-term frequency stability benefits from the implementation of additional stabilization loops to reduce temperature-induced light-shift effects. In this article, we report and highlight the individual and combined benefits of such servo loops on the frequency stability of a CPT-based MAC. The first loop stabilizes the actual temperature of the vertical-cavity surface-emitting laser (VCSEL) chip using a compensation method in which the reading of external temperature variations is derived from the atomic vapor output signal. The second loop maintains the total microwave power absorbed by the laser to a value that maximizes the optical absorption and significantly reduces the laser power dependence of the clock frequency. Experimental tests are performed onto a miniaturized CPT-clock physics package using a chip-VCSEL tuned on the Cs $D_{1}$ line ($\lambda =895$ nm). The VCSEL temperature compensation technique improves, by a factor of 4, the Allan deviation of the clock at 104 s. The simultaneous operation of both servo loops improves, by a factor of 7, the clock fractional frequency stability at 104 s. The clock demonstrates a fractional frequency stability of $7.5\times 10 ^{-11}$ at 1 s and better than $2\times 10^{-11}$ at 1 day. [ABSTRACT FROM AUTHOR]

This paper reports a dedicated theoretical and experimental study on the properties (signal amplitude and linewidth) of coherent population trapping resonances detected in vacuum vapor cells. Results are presented for conventional single-lambda schemes of atomic energy levels but also for double-lambda schemes, now widely used in various applications including atomic clocks and magnetometers. Approximate compact analytical expressions, valid for a wide range of light-wave intensities, i.e., beyond the low intensities or pump-probe regime, have been obtained. Analytical results are found to be in excellent agreement with exact numerical solutions based on the optical Bloch equations. Experimental results, obtained in a Cs vapor microfabricated cell, are reported and found to be in correct agreement with theoretical expressions. [ABSTRACT FROM AUTHOR]

Atomic level characterization brings fundamental insight into the mechanisms of self-protection against corrosion of metals and alloys by oxide passive films and into how localized corrosion is initiated on passivated metal surfaces. This is illustrated in this overview with selected data obtained at the subnanometre, i.e. atomic or molecular, scale and also at the nanometre scale on singlecrystal copper, nickel, chromium and stainless steel surfaces passivated in well-controlled conditions and analysed in situ and/or ex situ by scanning tunnelling microscopy/spectroscopy and atomic force microscopy. A selected example of corrosion modelling by ab initio density functional theory is also presented. The discussed aspects include the surface reconstruction induced by hydroxide adsorption and formation of two-dimensional (hydr)oxide precursors, the atomic structure, orientation and surface hydroxylation of three-dimensional ultrathin oxide passive films, the effect of grain boundaries in polycrystalline passive films acting as preferential sites of passivity breakdown, the differences in local electronic properties measured at grain boundaries of passive films and the role of step edges at the exposed surface of oxide grains on the dissolution of the passive film. This article is part of the themed issue 'The challenges of hydrogen and metals'. [ABSTRACT FROM AUTHOR]

Porous TiN xO y-based particles were synthesized by an aerosol spray process. At first, the starting sol solution containing the metal precursor and the nitrogen source is sprayed to form an aerosol that is subsequently pyrolysed at different temperatures. The obtained dried particles are an amorphous coordination 'polymer' rich in carbon and nitrogen. These 'glassy' particles are finally thermally treated at 800 °C, promoting the crystallization of the particles and the release of a major part of the carbon. As the particles keep their original shape, carbon loss and density increase during the crystallization step and lead to the development of an accessible pore structure. The process was analyzed and extended to the synthesis of other metal nitrides, such as VN and W2N, thereby showing its general validity for the production of functional nanocrystalline nitride ceramics with high porosity still occupying a relatively small volume, and otherwise not easily accessible. [ABSTRACT FROM AUTHOR]

Electrochemical scanning tunneling microscopy (ECSTM) was applied to analyze in situ the passivation of grain boundaries on microcrystalline copper in 0.1 M NaOH aqueous solution. Two types of boundaries, assigned to coherent twin and random grain boundaries, were studied in three different states of the copper surface: metallic after cathodic reduction of the air-formed native oxide film, passive after anodic polarization at 0.7 V vs. SHE to form the duplex Cu(I)/Cu(II) oxide film, and metallic after cathodic reduction of the passive film. The depth measured at several sites along the grain boundaries was extracted from statistical line profile analysis and discussed using an original model allowing differentiating metal consumption by dissolution or by passive film formation at grains and grain boundaries. The results highlight different local passivation properties between randomly oriented grains and grain boundaries and also between the two different types of grain boundaries. Both at coherent twin and random grain boundaries, it is found that more copper irreversibly dissolves during passivation and less copper is consumed to grow the passive film, suggesting a more hydroxylated/hydrated composition less dense in copper than on grains. At random grain boundaries, irreversible dissolution is found to be enhanced and the passive film to be thicker. [ABSTRACT FROM AUTHOR]

The article focuses on topics related to corrosion control. Topics include use of density functional theory (DFT) for hydrocarbons, polymer coatings for substrates in the presence of an oxide film, and presence of graphene on the diamond surface. Also discussed are topics like control of hydrogen ion (pH) concentration during polymeric coating process.

The article focuses on electrochemical hydrogen production, electron emission from solids, and atomic force microscopy (AFM) imaging for diffraction measurement. Topics include use of magnesium electrodes, kinetic energy of photoelectrons and binding energy of electrons, and Bragg peaks and Bragg regions.

The article focuses on various topics related to corrosion. Topics include the use of zinc oxide as a semiconducting oxide, formation of oxide films, and the effect of oxygen on copper. Also discussed are topics like sensitivity of metal ions, corrosion due to carbon dioxide in oil industry, and ultra high vacuum treatment.

Surface analysis by time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy and scanning tunnelling microscopy has been applied to provide new insight on Mo effects on the composition and nanostructure of the passive films grown in sulfuric acid on well-controlled Fe–17Cr–14.5Ni–2.3Mo(100) austenitic stainless steel single crystal surfaces. A duplex hydroxylated oxide matrix, 1.8–1.9 nm thick, is formed with a strong partition between Cr(iii) and Fe(iii) in the inner and outer layers, respectively. Cr(iii) is increasingly enriched by preferential iron oxide dissolution upon passivation and ageing. Ni, only present as oxide traces in the film, is enriched in the alloy underneath. Mo, mostly present as Mo(iv) in the Cr-rich inner layer prior to anodic polarisation, becomes increasingly enriched (up to 16% of cations) mostly as Mo(vi) in the Fe-rich outer layer of the passive film, with ageing promoting this effect. Metallic Mo is not significantly enriched below the passive film produced from the native oxide covered surface. Mo does not markedly impact the nanogranular morphology of the native oxide film nor its local thickness variations assigned to substrate site effects on Cr(iii) enrichment. Site specific preferential passivation still takes place at the (native) oxide-covered step edges of the alloy surface, and transient dissolution remains preferentially located on the terraces. Nanostructures, possibly Mo-containing, and healing local depressions formed by transient dissolution during passivation, appear as a specific effect of the Mo presence. Another Mo effect, observed even after 20 h of passivation, is to prevent crystallisation at least in the Fe-rich outer part of the passive film where it is concentrated mostly as Mo(vi) (i.e. molybdate) species. [ABSTRACT FROM AUTHOR]

The chemical and morphological modifications of FeS thin film as anode material for LiBs have been studied in detail in two classical electrolytes usually used in Li-ion batteries: 1 M LiClO4-PC and 1 M LiPF6-EC/DMC. The X-ray photoelectron spectroscopic (XPS) analysis evidenced the formation of a solid electrolyte interphase (SEI) that contains a more significant amount of inorganic salt residues formed in LiPF6-EC/DMC than in LiClO4-PC, which is likely to increase the ionic resistivity of the SEI, thus impeding the lithiation--delithiation in the first cycles while improving its reversibility. Ion depth profiles performed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) show volume expansion-shrinkage of the thin film leading to cracking and pulverization of the electrode material, which is also confirmed by scanning electron microscopy (SEM) analysis. The prolonged cycling results in penetration and accumulation of the electrolyte in a bulk electrode with accumulation of the inorganic species in the inner part of the SEI enhanced in a fluoride-containing electrolyte. Cycling in these two different electrolytes leads also to formation of two different electrode morphologies: with a compact electrode structure formed in LiClO4-PC and a foam-like, porous structure in LiPF6-EC/DMC. A model of this conversion-type thin film electrode modification based on these thorough spectroscopic and microscopic analyses induced by cycling in two different electrolytes is proposed. [ABSTRACT FROM AUTHOR]

Atomic layer deposited (ALD) 50 nm Al xTa yO z mixture coatings are grown on steel for corrosion protection. In morphological and compositional analyses the coatings are found to be uniform, conformal, well-adhered, and low in defect density. Corrosion protection properties are evaluated with polarization measurements and neutral salt spray (NSS) testing. The sealing properties of the mixtures improve with increasing aluminum oxide content, whereas the protection durability improves with increasing tantalum oxide content. In comparison to single-layer and nano-laminate ALD Al2O3 and Ta2O5 coatings, all mixtures are found to have better protective properties. [ABSTRACT FROM AUTHOR]

Pegylated silicon nanoparticles (SiNPs) are of great interest for applications in bio-imaging as fluorescent tracers. Poly(ethylene glycol) (PEG) covalently attached to SiNPs may improve the (bio)compatibility, solubility in water and stability of SiNPs, without inhibiting their optical properties. SiNPs are first coated with silica followed by a silanization of the surface. Then, two versatile 'grafting to' methods are used to provide pegylated SiNPs. Both peptide type coupling and copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) are conducted and compared to graft PEG of different chain lengths. Infra-red spectroscopy, thermogravimetric analysis and transmission electron microscopy prove that theses methodologies are simple and efficient for the preparation of functional inorganic nanoparticles with luminescent properties. [ABSTRACT FROM AUTHOR]

This article presents a process for surface coating and functionalization of luminescent silicon nanoparticles. The particles were coated with silica using a microemulsion process that was adapted to the fragile silicon nanoparticles. The as-produced core-shell particles have a mean diameter of 35 nm and exhibit the intrinsic photoluminescence of the silicon core. The silica layer protects the core from aqueous oxidation for several days, thus allowing the use of the nanoparticles for biological applications. The nanoparticles were further coated with amines and functionalized with polyethylene glycol chains and the toxicity of the particles has been evaluated at the different stages of the process. The core-shell nanoparticles exhibit no acute toxicity towards lung cells, which is promising for further development. [ABSTRACT FROM AUTHOR]

This article deals with the first covalent grafting of an enzyme on twice functionalized γ-Fe2O3@SiO2 core–shell magnetic nanoparticles. First, amino-PEG functionalized nanoparticles were synthesized in order to comply with non-toxic platforms that would be stable in high concentration and would exhibit chemical groups to allow further coupling with biomolecules. This approach produces a colloidal suspension of covalently grafted enzymes that remains stable for months and mimics the enzyme–substrate interactions in solution. Secondly, nanoparticles synthesis and enzyme coupling process were reported and the catalytic properties of bound enzymes were measured and compared with that of the free one. These new materials appear to be useful tools for enzymatic catalysis research and may be extended to other biomolecules. Furthermore, magnetic properties of these materials open the way to separation, purification, and transport under magnetic field. [ABSTRACT FROM AUTHOR]

Oxide layers grown on the surface provide an effective way of protecting metallic materials against corrosion for sustainable use in a broad range of applications. However, the growth of cavities at the metal/oxide interface weakens the adherence of the protective layer and can promote its spallation under service conditions, as observed for alumina layers formed by selective oxidation of aluminide intermetallic alloys used in high-temperature applications. Here we show that direct atomic-scale observations of the interface between an ultrathin protective oxide layer (alumina) grown on an intermetallic titanium aluminide substrate (TiAl) can be performed with techniques sensitive to the topmost atomic layers at the surface. Nanocavities resulting from the self-assembling of atomic vacancies injected at the interface by the growth mechanism of the protective oxide are observed for the first time, bringing new insight into the understanding of the fate of injected cavities in oxidation processes. [ABSTRACT FROM AUTHOR]

The initial stages of growth of ordered layers of Al[sub 2]O[sub 3] on NiAl(001) single-crystal surfaces at 1025 K and 10[sup -7] mbar (10[sup -5]Pa) in O[sub 2] have been studied using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). The STM results evidence the formation of elongated strips (26 Å wide and 11 Å high) of Al[sub 2]O[sub 3] oriented along the [100] and [010] directions of the substrate. With longer oxidation, the substrate is increasingly covered by rectangular and striped islands resulting from the vicinal and parallel growth of the strips. On the ultrathin oxide film formed after 500 L (1 L = 10[sup -6] torr-s (∼1.33 × 10[sup -4] Pa·s)) of exposure, STM atomic resolution images have been obtained for the first time. They evidence the [001] orientation of the oxygen sublattice in Bain epitaxy on the substrate. The observation of one-dimensional atomic trenches together with the strips observed on the nanometer scale is consistent with the growth of θ-Al[sub 2]O[sub 3]. The STS local measurements evidence the insulating behavior of the oxide layer formed with a gap value ranging from 7 and 8 eV for amorphous and ordered domains, respectively. [ABSTRACT FROM AUTHOR]

We show that micro-machined non-evaporable getter pumps (NEGs) can extend the time over which laser cooled atoms can be produced in a magneto-optical trap (MOT), in the absence of other vacuum pumping mechanisms. In a first study, we incorporate a silicon-glass microfabricated ultra-high vacuum (UHV) cell with silicon etched NEG cavities and alumino–silicate glass (ASG) windows and demonstrate the observation of a repeatedly-loading MOT over a 10 min period with a single laser-activated NEG. In a second study, the capacity of passive pumping with laser activated NEG materials is further investigated in a borosilicate glass-blown cuvette cell containing five NEG tablets. In this cell, the MOT remained visible for over 4 days without any external active pumping system. This MOT observation time exceeds the one obtained in the no-NEG scenario by almost five orders of magnitude. The cell scalability and potential vacuum longevity made possible with NEG materials may enable in the future the development of miniaturized cold-atom instruments. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

Stainless steels are widely used as metal components owing to self-protection in aggressive environments, provided by an extremely thin surface oxide film enriched in chromium oxide. Yet, despite decades of research, the mechanisms distributing the chromium enrichment at small length scale are poorly understood, although it may cause loss of stability and local failure of the corrosion resistance. Here, we apply high resolution surface analysis to investigate at small time and length scales the nucleation and growth mechanisms of the surface oxide on a model stainless steel. Starting from an oxide-free surface, we report the direct observation of the oxide nucleation and local oxidation of chromium, which governs the nanoscale heterogeneity of the growing surface oxide by chromium pumping from the atomic terraces to the steps for preferential Cr(III) oxide nucleation and subsequently by segregation from the atomic planes below to grow the Cr(III) layer incompletely saturating the stainless steel surface. This work provides new insight on corrosion chemistry, by evidencing local chemical and structural defects self-generated at the nanoscale by the building process of the protective oxide barrier, and affecting the passive film stability. [ABSTRACT FROM AUTHOR]

The efficient light–matter interaction and discrete level structure of atomic vapors made possible numerous seminal scientific achievements including time-keeping, extreme non-linear interactions, and strong coupling to electric and magnetic fields in quantum sensors. As such, atomic systems can be regarded as a highly resourceful quantum material platform. Recently, the field of thin optical elements with miniscule features has been extensively studied demonstrating an unprecedented ability to control photonic degrees of freedom. Hybridization of atoms with such thin optical devices may offer a material system enhancing the functionality of traditional vapor cells. Here, we demonstrate chip-scale, quantum diffractive optical elements which map atomic states to the spatial distribution of diffracted light. Two foundational diffractive elements, lamellar gratings and Fresnel lenses, are hybridized with atomic vapors demonstrating exceptionally strong frequency-dependent, non-linear and magneto-optic behaviors. Providing the design tools for chip-scale atomic diffractive optical elements develops a path for compact thin quantum-optical elements. Quantum coherence and the nonlinear properties of atoms are highly useful in optical devices. Here the authors show quantum-optic hybrid platforms in fully integrated chip-scale atomic diffractive optical elements by embedding hot atomic Rb vapor in microfabricated structures in silicon. [ABSTRACT FROM AUTHOR]

This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm. [ABSTRACT FROM AUTHOR]