Disulfide-Containing Nitrosoarenes: Synthesis and Insights into Their Self-Polymerization on a Gold Surface.

Disulfide-containing nitrosoarenes with [bis(4-nitrosobenzyl) disulfide, ()] or without [4-nitrosophenyl disulfide, (), and 1,2-bis(4'-nitroso-[1,1'-biphenyl]-4-yl)disulfane, ()] an alkyl spacer between the sulfur headgroup and the aromatic moiety (phenyl in () or biphenyl in ()) were synthesized and used as precursors to form azodioxy thiolate films on Au(111) substrates. Due to the incorporated disulfide functionalities, these specifically designed nitrosoarenes are enabled to self-polymerize through azodioxy bonds on a gold surface. Thin films of (), (), and () were prepared at different adsorption times via the solution-phase self-assembly of molecules onto the Au(111) surface and characterized by Raman spectroscopy, ellipsometry, water contact angle measurements, atomic force microscopy (AFM), and scanning tunneling microscopy (STM).

Strain-Enhanced Large-Area Monolayer MoS Photodetectors.

In this study, we show a direct correlation between the applied mechanical strain and an increase in monolayer MoS photoresponsivity. This shows that tensile strain can improve the efficiency of monolayer MoS photodetectors. The observed high photocurrent and extended response time in our devices are indicative that devices are predominantly governed by photogating mechanisms, which become more prominent with applied tensile strain.

Unidirectional Nano-modulated Binding and Electron Scattering in Epitaxial Borophene.

A complex interplay between the crystal structure and the electron behavior within borophene renders this material an intriguing 2D system, with many of its electronic properties still undiscovered. Experimental insight into those properties is additionally hampered by the limited capabilities of the established synthesis methods, which, in turn, inhibits the realization of potential borophene applications. In this multimethod study, photoemission spectroscopies and scanning probe techniques complemented by theoretical calculations have been used to investigate the electronic characteristics of a high-coverage, single-layer borophene on the Ir(111) substrate.

van der Waals 2D transition metal dichalcogenide/organic hybridized heterostructures: recent breakthroughs and emerging prospects of the device.

The near-atomic thickness and organic molecular systems, including organic semiconductors and polymer-enabled hybrid heterostructures, of two-dimensional transition metal dichalcogenides (2D-TMDs) can modulate their optoelectronic and transport properties outstandingly. In this review, the current understanding and mechanism of the most recent and significant breakthrough of novel interlayer exciton emission and its modulation by harnessing the band energy alignment between TMDs and organic semiconductors in a TMD/organic (TMDO) hybrid heterostructure are demonstrated. The review encompasses up-to-date device demonstrations, including field-effect transistors, detectors, phototransistors, and photo-switchable superlattices.

Colorimetric paper test strips based on cesium lead bromide perovskite nanocrystals for rapid detection of ciprofloxacin hydrochloride.

The detection of drugs containing hydrochloric salt with conventional methods is time consuming and expensive. In this work, upon exposure to ciprofloxacin hydrochloride at different concentrations, the emission from CsPbBrNCs shifts to the blue from 513 nm to 442 nm. CsPbBrClNCs are formed by the ion exchange and substitution of Brand Clions from surface to core of NCs.

Electronic Structure of Quasi-Freestanding WS/MoS Heterostructures.

Growth of 2D materials under ultrahigh-vacuum (UHV) conditions allows for an in situ characterization of samples with direct spectroscopic insight. Heteroepitaxy of transition-metal dichalcogenides (TMDs) in UHV remains a challenge for integration of several different monolayers into new functional systems. In this work, we epitaxially grow lateral WS-MoS and vertical WS/MoS heterostructures on graphene.

Two Phases of Monolayer Tantalum Sulfide on Au(111).

We prepared monolayers of tantalum sulfide on Au(111) by evaporation of Ta in a reactive background of HS. Under sulfur-rich conditions, monolayers of 2H-TaS formed, whereas under sulfur-poor conditions TaS with 0 ≤ ≤ 1 were found. We identified this phase as TaS, a structure that can be derived from 2H-TaS by removal of the bottom S layer.

Investigation of Ion Irradiation Effects in Silicon and Graphite Produced by 23 MeV I Beam.

Both silicon and graphite are radiation hard materials with respect to swift heavy ions like fission fragments and cosmic rays. Recrystallisation is considered to be the main mechanism of prompt damage anneal in these two materials, resulting in negligible amounts of damage produced, even when exposed to high ion fluences. In this work we present evidence that these two materials could be susceptible to swift heavy ion irradiation effects even at low energies.

Linewidth Narrowing with Ultimate Confinement of an Alkali Multipole Plasmon by Modifying Surface Electronic Wave Functions with Two-Dimensional Materials.

This work demonstrates significant line narrowing of a surface multipole plasmon (MP) by modifying the surface electronic wave function with two-dimensional materials (2DMs): graphene and hexagonal boron nitride. This is found in an optical reflectivity of alkali atoms (Cs or K) on an Ir(111) surface covered with the 2DMs. The reduction in reflectivity induced by deposition of the alkali atoms becomes as large as 20% at ∼2  eV, which is ascribed to a MP of a composite of alkali/2DM/alkali/Ir multilayer structure.

Cluster Superlattice Membranes.

Cluster superlattice membranes consist of a two-dimensional hexagonal lattice of similar-sized nanoclusters sandwiched between single-crystal graphene and an amorphous carbon matrix. The fabrication process involves three main steps, the templated self-organization of a metal cluster superlattice on epitaxial graphene on Ir(111), conformal embedding in an amorphous carbon matrix, and subsequent lift-off from the Ir(111) substrate. The mechanical stability provided by the carbon-graphene matrix makes the membrane stable as a free-standing material and enables transfer to other substrates.

Anomalous Temperature Dependence of Exciton Spectral Diffusion in Tetracene Thin Film.

In this work, an ultrafast spectral diffusion of the lowest exciton in a tetracene ultrathin film is studied by two-dimensional electronic spectroscopy. From the analysis of the nodal line slope, the frequency-fluctuation correlation function (FFCF) of the exciton band is extracted. The FFCF contains two components with decay times of 400 and 80 fs; while the former can be understood by a linear exciton-phonon coupling model, the latter shows an order of magnitude increase in its amplitude from 96 to 186 K that cannot be explained by the same model.

Atomic-scale defects and electronic properties of a transferred synthesized MoS monolayer.

MoS monolayer samples were synthesized on a SiO/Si wafer and transferred to Ir(111) for nano-scale characterization. The samples were extensively characterized during every step of the transfer process, and MoS on the final substrate was examined down to the atomic level by scanning tunneling microscopy (STM). The procedures conducted yielded high-quality monolayer MoS of milimeter-scale size with an average defect density of 2 × 10 cm.

Nematic topological defects positionally controlled by geometry and external fields.

Using a Landau-de Gennes approach, we study the impact of confinement topology, geometry and external fields on the spatial positioning of nematic topological defects (TDs). In quasi two-dimensional systems we demonstrate that a confinement-enforced total topological charge of > 1/2 decays into elementary TDs bearing a charge of = 1/2. These assemble close to the bounding substrate to enable essentially bulk-like uniform nematic ordering in the central part of a system.

The backside of graphene: manipulating adsorption by intercalation.

The ease by which graphene is affected through contact with other materials is one of its unique features and defines an integral part of its potential for applications. Here, it will be demonstrated that intercalation, the insertion of atomic layers in between the backside of graphene and the supporting substrate, is an efficient tool to change its interaction with the environment on the frontside. By partial intercalation of graphene on Ir(111) with Eu or Cs we induce strongly n-doped graphene patches through the contact with these intercalants.

Mapping image potential states on graphene quantum dots.

Free-electron-like image potential states are observed in scanning tunneling spectroscopy on graphene quantum dots on Ir(111) acting as potential wells. The spectrum strongly depends on the size of the nanostructure as well as on the spatial position on top, indicating lateral confinement. Analysis of the substructure of the first state by the spatial mapping of the constant energy local density of states reveals characteristic patterns of confined states.

The Bernese periacetabular osteotomy: clinical, radiographic and mechanical 7-15-year follow-up of 26 hips.

Background: The Bernese periacetabular osteotomy is used in dysplastic hips to increase the load-bearing area of the hip and to prevent osteoarthritis. The aim of our work was to determine the contact hip stress before and after the osteotomy and to compare the relief of stress with the long-term radiographic and clinical outcome.

Patients And Methods: We followed 26 dysplastic hips (26 patients) for 7-15 years after the index operation.