We present a first investigation of structural properties of Ag clusters with a diameter of up to 5.5 nm grown inside superfluid helium nanodroplets (He(N)) and deposited on an amorphous C surface. With high resolution transmission electron microscope images we are able to show that in addition to the crystalline face centered cubic (fcc) structure, noncrystalline icosahedral (Ih), and decahedral (Dh) morphologies are grown. Relative abundances (56% fcc, 31% Dh, and 13% Ih) as well as the size distribution of each morphology (mean diameters d(fcc)=2.62(5) nm, d(Dh)=3.34(7) nm, and d(Ih)=3.93(2) nm) do not reflect the situation expected from pure energetic considerations, where small Ihs should be followed by medium sized Dhs and large fccs. Instead, kinetic factors seem to play an important role in the formation of these structures, as it appears to be the case for clusters formed by inert gas aggregation. Considering the low temperatures (0.37 K) and extremely high cooling rates, we discuss basic ideas that might lead to a qualitative picture of the cluster formation process inside He(N).

A new method for nanostructure formation from conjugated polymers is presented: an aqueous dispersion of semiconducting polymer nanospheres (SPNs) is deposited by inkjet printing onto a polymer surface patterned by soft embossing. By interaction between the spheres and the undulated surface a self assembly process is triggered, resulting in the formation of SPN nanostructures determined by the template. Both template layer and assembled SPNs can be incorporated into a device structure. We demonstrate a light emitting structure for use in polymer light emitting devices including analyses by atomic force microscopy and Kelvin probe force microscopy.

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An aqueous dispersion of semiconducting polymer nanospheres was used to fabricate polymer light-emitting devices by inkjet printing in an easy-to-apply process with a minimum feature size of 20μm. To form the devices, the electroluminescent material was printed on a nonemitting polystyrene matrix layer and embedded by thermal annealing. The process allows the printing of light-emitting thin-film devices without extensive optimization of film homogeneity and thickness of the active layer. Optical micrographs of printed device arrays, electroluminescence emission spectra, and I∕V characteristics of printed ITO/PEDOT:PSS/PS/SPN/Al devices are presented.

Irradiation damage, caused by the use of beams in the electron microscopes, leads to undesired physical/chemical material property changes or uncontrollable modification of structures that are being processed. Particularly, soft matter such as polymers or biological materials is highly susceptible and very much prone to react on irradiation by electron and ion beams. The effect is even higher when materials are subjected to energetic species such as ions that possess high momentum and relatively low mean path due to their mass. Especially when Ga(+) ions (used as the ion source in Focused Ion Beam (FIB) instruments) are considered, the end-effect might even be the total loss of the material's properties. This paper will discuss the possible types of degradation mechanisms and defect formations that can take place during ion and electron beam irradiation of the conjugated polymers: e.g. polyfluorene (PF) and poly-3-hexylthiophene (P3HT) thin films. For the investigation of the irradiation induced degradation mechanisms in this study, complementary analytical techniques such as Raman Spectroscopy (RS), Infrared Spectroscopy (IR), Electron Energy Loss Spectroscopy (EELS), Atomic Force Microscopy (AFM), and Fluorescence Microscopy including Photoluminescence (PL) and Electroluminescence (EL) Microscopy were applied.

Intrinsically magnetic layered materials – especially monolayers – suffer from the lack of ambient stability and mostly exhibit magnetic ordering only at cryogenic temperatures. These restrains impose a great challenge for the integration of two-dimensional magnetic materials into future technologies. We propose to overcome this by exploiting phyllosilicates, such as iron-rich talc. Via combined magnetic force microscopy in applied external magnetic fields, superconducting quantum interference device magnetometry, first-principle calculations, and structural analysis, we demonstrate that incorporated iron ions in talc are in a very robust high spin state, resulting in a weak ferromagnetic behavior at room temperature. Iron-rich talc can be thinned down to a monolayer, remaining fully stable under ambient conditions, and retaining magnetic properties even in monolayers. Finally, we propose iron-rich end members of the phyllosilicates as very promising platforms for air-stable magnetic monolayers.

In this study, to assess the influence of the temperature on the ion beam degradation, irradiation experiments on organic semiconductor materials were performed for both cryogenic and room temperature conditions. Thin P3HT films on silicon substrates were exposed to increasing ion doses in dual beam FIB. The degradation behaviour by means of a decrease in the C[double bond, length as m-dash]C band which corresponds to a loss of conjugation was investigated by means of Raman spectroscopy. In addition, atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM) were used for a characterization of morphology and surface potential which provide information on temperature and ion dose dependent degradation behaviour.

Optical sensors have been a field of intensive academic as well as industrial research over the last three decades. Clark-type electrodes, [1] for example, have been a standard for many years in oxygen detection; however, they are more and more replaced by optical sensors. Different optical sensor systems, e.g., fiber optic [2] or planar waveguide [3] based platforms, were developed using the optical properties of the analyte itself as well as changes of the optical properties of an intermediate indicator molecule (e.g., organometallic compounds) for analyte detection.To yield analyte information, most common optical transduction techniques used in optical chemical sensors are based on fluorescence [4] or absorption measurements (e.g., nondispersive infrared sensors [5] ). In this context, the class of so-called direct sensors uses a modification of an intrinsic optical property of the analyte, whereas in the case of inappropriate intrinsic optical properties an intermediate analyte-sensitive dye molecule has to be added. The presence of the corresponding analyte alters the optical properties of the indicator dye, thus allowing its detection. Such a sensing technique requires, depending on the phase of the analyte, in most cases an immobilization of the dye within a matrix layer, which provides analyte accessibility but prevents leaching effects. Different approaches for immobilization of indicators within a matrix material have been realized up to now, such as covalent [6,7] bonding or simple encapsulation.[8] Apart from analyte diffusion coefficients within the matrix, [9] sensitivity as well as sensor response time strongly depend on indicatormatrix interactions.[10] Due to these interactions, spectroscopic shifts [11] and enhanced or reduced excited state lifetimes [12,13] are frequently observed in the solid state compared to solution. Nevertheless, embedding the dye molecule within a rigid matrix enhances the photostability due to reduced ligand photodegradation. [14] Along this line, optical oxygen probes commonly use platinum [15] or palladium [16] based organometallic complexes as indicator molecules. Spin orbit coupling is enhanced because of the metal ion within the organic complex; this enables an efficient radiative decay from the lowest triplet state to the singlet ground state of the molecule (phosphorescence). Because spin orbit coupling is weak in fluorescent materials, a radiative decay from an excited triplet state is unlikely. The phosphorescence lifetime of organometallic complexes is, depending on the transient metal complex and the matrix material, in the range of microseconds, which is several orders of magnitude larger than the fluorescent excited state lifetime. Most reagent-mediated optical oxygen sensors use dynamic interactions between the excited state of the dye molecule and the analyte. Since molecular contact is required for this kind of interaction, the analyte has to reach the immobilized dye molecule within its excited state lifetime. Taking into consideration the physical para...