Morphology and Mechanics of Star Copolymer Ultrathin Films Probed by Atomic Force Microscopy in the Air and in Liquid.

Star copolymer films were produced by using spin-coating, drop-casting, and casting deposition techniques, thus obtaining ultrathin and thick films, respectively. The morphology is generally flat, but it becomes substrate-dependent for ultrathin films where the planarization effect of films is not efficient. The indentation hardness of films was investigated by Force Volume Maps in both the air and liquid.

Recycled or Bio-Based Solvents for the Synthesis of ZnO Nanoparticles: Characterization and Validation in Organic Solar Cells.

Among solution-processable metal oxides, zinc oxide (ZnO) nanoparticle inks are widely used in inverted organic solar cells for the preparation, at relatively low temperatures (<120 °C), of highly efficient electron-transporting layers. There is, however, a recent interest to develop more sustainable and less impacting methods/strategies for the preparation of ZnO NPs with controlled properties and improved performance. To this end, we report here the synthesis and characterization of ZnO NPs obtained using alternative reaction solvents derived from renewable or recycled sources.

Native Silicon Oxide Properties Determined by Doping.

The physico-chemical properties of native oxide layers, spontaneously forming on crystalline Si wafers in air, can be strictly correlated to the dopant type and doping level. In particular, our investigations focused on oxide layers formed upon air exposure in a clean room after Si wafer production, with dopant concentration levels from ≈10 to ≈10 cm. In order to determine these correlations, we studied the surface, the oxide bulk, and its interface with Si.

Identification of ultra-thin molecular layers atop monolayer terraces in sub-monolayer organic films with scanning probe microscopy.

The morphology of sub-monolayer sexithiophene films has been investigated in situ and ex situ as a function of the substrate temperature of deposition. In this thickness range, monolayer terraces formed of edge-on molecules, i.e.

Synthesis, Crystal Structure, and Antibacterial Properties of Silver-Functionalized Low-Dimensional Layered Zirconium Phosphonates.

New insoluble layered zirconium phosphate carboxyaminophosphonates (ZPs), with the general formula Zr(PO)H[(OPCH)N(CH)COO]·HO ( = 3, 4, and 5), have been prepared and characterized. The crystal structure for = 3 and 4 samples was determined from X-ray powder diffraction data. The structure for = 3 was monoclinic in space group 2/ with the following unit cell parameters: = 34.

Differential Entropy: An Appropriate Analysis to Interpret the Shape Complexity of Self-Similar Organic Islands.

Differential entropy, along with fractal dimension, is herein employed to describe and interpret the shape complexity of self-similar organic islands. The islands are imaged with in situ Atomic Force Microscopy, following, step-by-step, the evolution of their shape while deposition proceeds. The fractal dimension shows a linear correlation with the film thickness, whereas the differential entropy presents an exponential plateau.

4H-SiC surface morphology after Al ion implantation and annealing with C-cap.

The root mean square (rms) surface roughness extracted from atomic force microscopy is widely employed to complement the characterisation of ion implantation processes in 4H-SiC. It is known that the protection of a carbon film eliminates or mitigates roughening of the SiC surface during postimplantation annealing. This study, based on a rich original data collection of Al ion implanted 4H-SiC samples, allows for a quantitative description of the surface morphology as a function of the annealing temperature and time and of the Al implanted concentration.

Amyloid fragments and their toxicity on neural cells.

The formation of amyloid fibrils from soluble proteins is a common form of self-assembly phenomenon that has fundamental connections with biological functions and human diseases. Lysozyme was converted from its soluble native state into highly organized amyloid fibrils. Ultrasonic treatment was used to break amyloid fibrils to fibrillar fragments-seeds.

3D to 2D reorganization of silver-thiol nanostructures, triggered by solvent vapor annealing.

Metal-organic composites are of great interest for a wide range of applications. The control of their structure remains a challenge, one of the problems being a complex interplay of covalent and supramolecular interactions. This paper describes the self-assembly, thermal stability and phase transitions of ordered structures of silver atoms and thiol molecules spanning from the molecular to the mesoscopic scale.

Nanoscale morphological analysis of soft matter aggregates with fractal dimension ranging from 1 to 3.

While the widespread emergence of nanoscience and nanotechnology can be dated back to the early eighties, the last decade has witnessed a true coming of age of this research field, with novel nanomaterials constantly finding their way into marketed products. The performance of nanomaterials being dominated by their nanoscale morphology, their quantitative characterization with respect to a number of properties is often crucial. In this context, those imaging techniques able to resolve nanometer scale details are clearly key players.

Amorphous Aggregation of Amyloid Beta 1-40 Peptide in Confined Space.

The amorphous aggregation of Aβ1-40 peptide is addressed by using micromolding in capillaries. Both the morphology and the size of the aggregates are modulated by changing the contact angle of the sub-micrometric channel walls. Upon decreasing the hydrophilicity of the channels, the aggregates change their morphology from small aligned drops to discontinuous lines, thereby keeping their amorphous structure.

Aggregation of Aß(25-35) on DOPC and DOPC/DHA bilayers: an atomic force microscopy study.

β amyloid peptide plays an important role in both the manifestation and progression of Alzheimer disease. It has a tendency to aggregate, forming low-molecular weight soluble oligomers, higher-molecular weight protofibrillar oligomers and insoluble fibrils. The relative importance of these single oligomeric-polymeric species, in relation to the morbidity of the disease, is currently being debated.

Self-organization of functional materials in confinement.

This Account aims to describe our experience in the use of patterning techniques for addressing the self-organization processes of materials into spatially confined regions on technologically relevant surfaces. Functional properties of materials depend on their chemical structure, their assembly, and spatial distribution at the solid state; the combination of these factors determines their properties and their technological applications. In fact, by controlling the assembly processes and the spatial distribution of the resulting structures, functional materials can be guided to technological and specific applications.

Influence of metal-support interaction on the surface structure of gold nanoclusters deposited on native SiO(x)/Si substrates.

The structure of small gold nanoclusters (around 2.5 nm) deposited on different silica-on-silicon (SiOx/Si) substrates is investigated using several characterization techniques (AFM, XRD, EXAFS and GISAXS). The grain morphology and the surface roughness of the deposited gold cluster layers are determined by AFM.

Quantitative analysis of scanning tunneling microscopy images of mixed-ligand-functionalized nanoparticles.

Ligand-protected gold nanoparticles exhibit large local curvatures, features rapidly varying over small scales, and chemical heterogeneity. Their imaging by scanning tunneling microscopy (STM) can, in principle, provide direct information on the architecture of their ligand shell, yet STM images require laborious analysis and are challenging to interpret. Here, we report a straightforward, robust, and rigorous method for the quantitative analysis of the multiscale features contained in STM images of samples consisting of functionalized Au nanoparticles deposited onto Au/mica.

Molecular reorganization in organic field-effect transistors and its effect on two-dimensional charge transport pathways.

Charge transport in organic thin film transistors takes place in the first few molecular layers in contact with the gate dielectric. Here we demonstrate that the charge transport pathways in these devices are extremely sensitive to the orientational defects of the first monolayers, which arise from specific growth conditions. Although these defects partially heal during the growth, they cause depletion of charge carriers in the first monolayer, and drive the current to flow in the monolayers above the first one.

Selective growth of α-sexithiophene by using silicon oxides patterns.

A process for fabricating ordered organic films on large area is presented. The process allows growing sexithiophene ultra-thin films at precise locations on patterned Si/SiO(x) substrates by driving the orientation of growth. This process combines the parallel local anodic oxidation of Si/SiO(x) substrates with the selective arrangement of molecular ultra-thin film.

Morphological and mechanical properties of alkanethiol Self-Assembled Monolayers investigated via BiModal Atomic Force Microscopy.

Alkanethiol Self-Assembly Monolayers (SAMs) were investigated by means of BiModal Atomic Force Microscopy. Morphological and mechanical properties show a parabolic trend vs. the chain length n, which is ascribed to the disorder at the SAMs/Au interface.

Ultrasonic force microscopy: detection and imaging of ultra-thin molecular domains.

The analysis of the formation of ultra-thin organic films is a very important issue. In fact, it is known that the properties of organic light emitting diodes and field effect transistors are strongly affected by the early growth stages. For instance, in the case of sexithiophene, the presence of domains made of molecules with the backbone parallel to the substrate surface has been indirectly evidenced by photoluminescence spectroscopy and confocal microscopy.

Layered distribution of charge carriers in organic thin film transistors.

Drain-source current in organic thin-film transistors has been monitored in situ and in real time during the deposition of pentacene. The current starts to flow when percolation of the first monolayer (ML) occurs and, depending on the deposition rate, saturates at a coverage in the range 2-7 MLs. The number of active layers contributing to the current and the spatial distribution of charge carriers are modulated by the growth mode.

Additive nanoscale embedding of functional nanoparticles on silicon surface.

We present a novel additive process, which allows the spatially controlled integration of nanoparticles (NPs) inside silicon surfaces. The NPs are placed between a conductive stamp and a silicon surface; by applying a bias voltage a SiO(2) layer grows underneath the stamp protrusions, thus embedding the particles. We report the successful nanoembedding of CoFe(2)O(4) nanoparticles patterned in lines, grids and logic structures.

Molecular scale energy dissipation in oligothiophene monolayers measured by dynamic force microscopy.

We perform a combined experimental and theoretical approach to establish the atomistic origin of energy dissipation occurring while imaging a molecular surface with an amplitude modulation atomic force microscope. We show that the energy transferred by a single nano-asperity to a sexithiophene monolayer is about 0.15 eV/cycle.

Parallel-local anodic oxidation of silicon surfaces by soft stamps.

We investigate the fabrication of nanometric patterns on silicon surfaces by using the parallel-local anodic oxidation technique with soft stamps. This method yields silicon oxide nanostructures 15 nm high, namely at least five times higher than the nanostructures made with local anodic oxidation using atomic force microscopy, and thanks to the size of the stamp enables one to pattern the surface across a centimetre length scale. To implement this technique, we built a machine to bring the metallized polydimethylsiloxane stamp in contact with the silicon surface, subsequently inserted in a sealed chamber with controlled relative humidity.