Search results for "Self-assembled monolayer"
showing 6 items of 46 documents
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…
Potential-assisted deposition of mixed alkanethiol self-assembled monolayers
2010
Abstract Preparation of self-assembled monolayers (SAMs) usually involves passive incubation. The recently developed potential-assisted deposition is indeed more selective as well as 100-fold faster than passive adsorption, thereby enhancing the reproducibility of the monolayer deposition. This article aims to identify the electrodeposition conditions necessary to prepare mixed alkanethiol SAMs on gold surface. Parameters such as concentrations in solution, electrode polarization and deposition time were examined for two chain lengths, C 3 (mercaptopropionic acid, MPA) and C 18 (octadecanethiol, ODT). The kinetics and composition of the SAMs were systematically characterized by reductive st…
Carboxylic derivatives of spin-crossover complexes in switchable materials and surfaces
2022
Los compuestos de transición de espín (SCO, de las siglas en inglés spin-crossover) son un ejemplo perfecto de biestabilidad molecular. La transición entre sus estados de alto y bajo espín (HS y LS, de las siglas en inglés, High Spin y Low Spin, respectivamente) se puede controlar mediante estímulos externos como la temperatura, presión, luz, por nombrar unos pocos. Esto los convierte en compuestos muy interesantes para aplicaciones tales como espintrónica, almacenamiento de memoria y dispositivos conmutables. El interés científico en este tipo de moléculas y la búsqueda de aplicaciones ha ido creciendo a lo largo de los años. Para ello, la deposición de dichos compuestos es el primer paso …