(chiral) Quantum well Rashba splitting in Sb monolayer on Au(111)

We present atomic and electronic structure investigations of Single-layer (110) surface of rhombohedral crystal formed Sb on Au(111) substrate. Low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) reveal a pure 2D Sb stripe structure with mirror symmetry broken along the x axis direction. The electronic band structure is determined by angle-resolved photoemission spectroscopy (ARPES). The significantly complex surface band structure results from a combination of a surface band originating from the three different azimuthal orientations of the (110) rhombohedral phase and Umklapp scattered branches of Au sp band. The experimental bands are compared to the calculated band structure of $3\times\sqrt{3}$ periodicity of Sb(110). Most of the experimental band dispersions are qualitatively reproduced by the theoretical band structure except Umklapp scattered surface band. Taking advantage of our DFT calculations, we found the quantum well(QW) Rashba splitting bands appear at both $\bar{\Gamma}$ point and $\bar{X}$ point. Considering the surface Brillouin zone (SBZ) relationship between Sb(110) sub-unit cell and Au(111) surface, the distinct in energy position of QW states at $\bar{\Gamma}$ point and $\bar{X}$ point is found be a combination of the relative spin-orbital coupling(SOC) and the buckling of Sb monolayer on Au surface that work together. The orbital decomposition of the Sb(110) projected band structure indicates hybridization between Sb py state and Au state can modify the spin splitting of QW states due to the intrinsic large SOC of Au state introduced into the QW states

Recent Progress in the Fabrication of Low Dimensional Nanostructures via Surface-Assisted Transforming and Coupling

Polymerization of functional organics into covalently cross-linked nanostructures via bottom-up approach on solid surfaces has attracted tremendous interest recently, due to its appealing potentials in fabricating novel and artificial low dimensional nanomaterials. While there are various synthetic approaches being proposed and explored, this paper reviews the recent progress of on-surface coupling strategies towards the synthesis of low dimensional nanostructures ranging from 1D nanowire to 2D network and describes their advantages and drawbacks during on-surface process and phase transformations, for example, from molecular self-assembly to on-surface polymerization. Specifically, Ullmann reaction is discussed in detail and the mechanism governing nanostructures’ transforming effect by surface treatment is exploited. In the end, it is summarized that the hierarchical polymerization combined with Ullmann coupling makes it possible to realize the selection of different synthetic pathways and phase transformations and obtain novel organometallic nanowire with metalorganic bonding

Disentangling Electron-Boson Interactions on the Surface of a Familiar Ferromagnet

We report energy renormalizations from electron-phonon and electron-magnon interactions in spin minority surface resonances on Ni(111). The different interactions are disentangled and quantified in strength $\lambda$, based on the characteristic shapes of their complex self-energies, and the largely different binding energies at which they occur. The observed electron-magnon interactions reveal a strong dependence on momentum and energy band position in the bulk Brillouin zone. In contrast, electron-phonon interactions from the same bands are observed to be practically momentum- and symmetry-independent. Additionally, a moderately strong ($\lambda>0.5$) electron-phonon interaction is observed from a `buried', near-parabolic spin majority band that does not cross the Fermi level.Comment: QuSpin 202

Emerging Characterizing Techniques in the Fine Structure Observation of Metal Halide Perovskite Crystal

Driven by its appealing application in the energy harvesting industry, metal halide perovskite solar cells are attracting increasing attention from various fields, such as chemistry, materials, physics, and energy-related industries. While the energy conversion efficiency of the perovskite solar cell is being investigated often by various research groups, the relationship between the surface structure and the property is still ambiguous and, therefore, becomes an urgent topic due to its wide application in the real environment. Recently, the fine structure characterization of perovskite crystals has been analysed by varying techniques, such as XRD, synchrotron-based grazing incidence XRD, XAFS, and STM, in addition to others. In this review article, we will summarize recent progresses in the monitoring of fine nanostructures of the surface and crystal structures of perovskite films, mainly by XAFS, XRD, and STM, focusing on the discussion of the relationship between the properties and the stability of perovskite solar cells. Furthermore, a prospective is given for the development of experimental approaches towards fine structure characterization

Tribological properties of oil-impregnated polyimide in double-contact friction under micro-oil lubrication conditions

Abstract Oil-impregnated porous polyimide (iPPI) materials are usually used as retainer for bearings. In these bearings, balls and rings, balls and retainers are two different kinds of contact. In this paper, the friction and wear properties of iPPI were investigated using steel (disc)—steel (ball)—iPPI (pin) double-contact friction test rig for simulating the actual contact in bearings. The results show that compared with that of iPPI—steel single contact, the friction coefficient of iPPI—steel in double contacts is lower and decreases with the amount of additional oil. The surface of iPPI in single contact suffers more wear compared with that in double contacts. Different from single contact, the worn surfaces of iPPI in double contacts are blackened. The Raman spectra of worn surfaces of balls and discs indicate that α-Fe2O3 and Fe3O4 were formed during rubbing of the double contacts. Many nanoscale iron oxide particles are found on the worn surfaces of iPPI in double contacts; on the contrary, few particles could be found on the surface in single contact. In double-contact friction, the nanoscale wear debris penetrates inside the iPPI material through the process of extruding and recycling of oil, which is the mechanism of the blackening of the iPPI worn surfaces. The studies show that the double-contact friction method is a new and effective method to study the friction in bearings, especially for those with polymer retainer

Kinetics and Thermodynamics Studies of Cationic Dye Adsorption onto Carboxymethyl Cotton Fabric

Cotton fiber is a very rich natural polysaccharide material in nature, which is usually dyed with reactive dyes. However, a large number of salts remain in the dye bath waste, polluting the ecological environment. In this study, the salt-free dyeing of cationic dyes on carboxymethyl cotton fabric modified with sodium chloroacetate was carried out under the conditions of pH 7, initial dye concentration 0.5–10% owf, and liquor ratio 1:100. The results demonstrated that the cationic dyes were successfully adsorbed on the modified cotton fabric in the absence of salt, but the dyeing fastness was low. Furthermore, the adsorption thermodynamics and kinetics were investigated. The adsorption kinetics was found to follow the pseudo-second-order kinetic model, and the adsorption isotherm obtained was identified to be the Langmuir type. These results will help us to realize the salt-free dyeing of carboxymethyl modified cotton fabric in the future

Rigid-flexible hybrid surfaces for water-repelling and abrasion-resisting

Droplets impacting solid superhydrophobic surfaces is appealing not only because of scientific interests but also for technological applications such as water-repelling. Recent studies have designed artificial surfaces in a rigid-flexible hybrid mode to combine asymmetric redistribution and structural oscillation water-repelling principles, resolving strict impacting positioning; however, this is limited by weak mechanical durability. Here we propose a rigid-flexible hybrid surface (RFS) design as a matrix of concave flexible trampolines barred by convex rigid stripes. Such a surface exhibits a 20.1% contact time reduction via the structural oscillation of flexible trampolines, and even to break through the theoretical inertial-capillary limit via the asymmetric redistribution induced by rigid stripes. Moreover, the surface is shown to retain the above water-repelling after 1,000 abrasion cycles against oilstones under a normal load as high as 0.2 N.mm(-1). This is the first demonstration of RFSs for synchronous waterproof and wearproof, approaching real-world applications of liquid-repelling.ISSN:2223-7704ISSN:2223-769