Search results for " monolayer"

The effect of long-chain bases on polysialic acid-mediated membrane interactions

2011

AbstractNegatively-charged polysialic acid (polySia) chains are usually membrane-bound and are often expressed on the surface of neuroinvasive bacterial cells, neural cells, and tumor cells. PolySia can mediate both repulsive and attractive cis interactions between membrane components, and trans interactions between membranes. Positively-charged long-chain bases are widely present in cells, are often localized in membranes and can function as bioactive lipids. Here we use Langmuir monolayer technique, fluorescence spectroscopy and electron microscopy of lipid vesicles to study the role of a simple long-chain base, octadecylamine (ODA), in both cis and trans interactions mediated by polySia …

Monolayer and multilayer field-effect transistors based on a high-mobility n-type polymer: effect of the polymeric texture on charge transport

2012

Photoluminescence Enhancement by Band Alignment Engineering in MoS 2 /FePS 3 van der Waals Heterostructures

2022

Single-layer semiconducting transition metal dichalcogenides (2H-TMDs) display robust excitonic photoluminescence emission, which can be improved by controlled changes to the environment and the chemical potential of the material. However, a drastic emission quench has been generally observed when TMDs are stacked in van der Waals heterostructures, which often favor the nonradiative recombination of photocarriers. Herein, we achieve an enhancement of the photoluminescence of single-layer MoS2 on top of van der Waals FePS3. The optimal energy band alignment of this heterostructure preserves light emission of MoS2 against nonradiative interlayer recombination processes and favors the charge t…

Introduction to Self-Assembled Monolayers

2015

One of the most exciting targets of molecular spintronics field is to go towards multifunctional devices where the properties can be accurately controlled and actively changed. Spin dependent hybridization at the metal/molecule interface could thus be used in the tailoring of the resistive and magnetoresistive response of spintronic devices exploiting chemistry versatility. In this new direction, Self-Assembled Monolayers (SAMs) appear as highly promising candidates since each part and function of this system can be modulated independently (like a molecular LEGO building unit). Despite highly promising, they are still scarcely investigated in the literature probably due to the difficulties …

Polystyrene nanoparticle-templated hollow titania nanosphere monolayers as ordered scaffolds

2018

We report a novel multi-step method for the preparation of ordered mesoporous titania scaffolds and show an illustrative example of their application to solar cells. The method is based on (monolayer) colloidal nanosphere lithography that makes use of polystyrene nanoparticles organised at a water–air interface and subsequently transferred onto a solid substrate. A titania precursor solution (titanium(IV) isopropoxide in ethanol) is then drop-cast onto the monolayer and left to “incubate” overnight. Surprisingly, instead of the expected inverse monolayer-structure, a subsequent calcination step of the precursor yields an ordered monolayer of hollow titania nanospheres with a wall thickness …

A metal-responsive interdigitated bilayer for selective quantification of mercury( ii ) traces by surface plasmon resonance

2016

Reusable surface plasmon resonance chips allowing the quantitative and selective detection of mercury(II) ions in water at the 0.01 nM level are reported. The surface-modified gold sensor consists of a rarefied self-assembled monolayer of octanethiol topped with a Langmuir–Blodgett monolayer of an amphiphilic and highly-specific chelator. The interdigitated architecture confers to the bilayer a high packing density, surface coverage, and binding-group accessibility.

Scanning tunneling microscopy investigation of tricycloquinazoline liquid crystals on gold

2000

Self-assembled monolayers (SAMs) of hexaalkylthioether derivatives of tricycloquinazoline (TCQ) on Au(111) and tungsten diselenide (WSe2) were investigated by scanning tunneling microscopy (STM). The Au(111) surfaces were found to be etched by the thioether containing solutions. Corroded surfaces which are similar to gold surfaces that were coated with SAMs of thiols or disulfides were revealed by STM. Atomic adsorption spectroscopy proved that an amount of gold that corresponds to ca. 30% of a monolayer was dissolved in the assembly solutions. On gold, the aromatic cores of the molecules were found to be in face-on orientation. The alkyl substituents were in most cases folded upwards and s…

SPM and TOF-SIMS investigation of the physical and chemical modification induced by tip writing of self-assembled monolayers

2003

Abstract The nanoelectrochemical modification of alkyl self-assembled monolayers (SAMs) obtained on hydrogenated silicon surfaces via radical-initiated reactions of 1-octadecene has been investigated. Scanning Probe Microscopy (SPM) showed that the modification of the organic layer occurs by applying either positive or negative biases to the tip at a threshold of about ±5 V. When the bias absolute value was ≤6 V, the height of the monolayer was only faintly modified, whereas a consistent increase in tip/sample friction force was observed, in agreement with the formation of hydrophilic moieties at the organic surface. In addition to the increase of friction, bias absolute values larger than …

<title>Optically induced switching of dicyclohexylamino substituted azobenzene derivatives in thin ordered films</title>

2005

During the last years, there has been an increasing interest in the photoinduced switching effects. Among the objects of concern azobenzene derivatives, isomerizing under UV and visible light, occupy a prominent position. To understand the photoresponse of these materials in the condensed phase, their spectroscopic and electrical properties are studied. It is shown that the photoresponse depends on the orientation of the molecules and their packing. A number of novel azobenzene derivatives containing a N,N-dicyclohexyl sulfonamide moiety is synthesized. The derivatives differ in the length of alkyl chains between the azobenzene moiety and SH or COOH groups. The morphology and the photoinduc…

Molecular nanostructures on ferromagnetic metals for spintronics

2017

El objetivo principal de esta tesis ha sido el estudio de la funcionalización de superficies ferromagnéticas mediante la formación de monocapas moleculares autoensambladas, (SAMs, self-assembled monolayers) con el fin de conseguir procesos sencillos y fiables para la preparación de interfaces híbridas aplicables en dispositivos de espintrónica molecular. La investigación se ha centrado en la funcionalización de materiales ferromagnéticos, concretamente el cobalto y la aleación de níquel:hierro conocida como Permalloy. Las propiedades magnéticas y de polarización de espín de estos metales ferromagnéticos se mantienen a temperatura ambiente, lo que los hace muy interesantes para su aplicación…