From Chains to Monolayers: Nanoparticle Assembly Driven by Smectic Topological Defects.

In this Letter, we show how advanced hierarchical structures of topological defects in the so-called smectic oily streaks can be used to sequentially transfer their geometrical features to gold nanospheres. We use two kinds of topological defects, 1D dislocations and 2D ribbon-like topological defects. The large trapping efficiency of the smectic dislocation cores not only surpasses that of the elastically distorted zones around the cores but also surpasses the one of the 2D ribbon-like topological defect.

Kossel Effect in Periodic Multilayers.

The Kossel effect is the diffraction by a periodically structured medium, of the characteristic X-ray radiation emitted by the atoms of the medium. We show that multilayers designed for X-ray optics applications are convenient periodic systems to use in order to produce the Kossel effect, modulating the intensity emitted by the sample in a narrow angular range defined by the Bragg angle. We also show that excitation can be done by using photons (X-rays), electrons or protons (or charged particles), under near normal or grazing incident geometries, which makes the method relatively easy to implement.

Note: Observation of the angular distribution of an x-ray characteristic emission through a periodic multilayer.

We present the observation of the angular distribution of a characteristic x-ray emission through a periodic multilayer. The emission coming from the substrate on which the multilayer is deposited is used for this purpose. It is generated upon proton irradiation through the multilayer and detected with an energy sensitive CCD camera.

Method for Determining the Polymer Content in Nonsoluble Polydiacetylene Films: Application to Pentacosadiynoic Acid.

The absorptivities of polydiacetylenes (PDAs) used in Langmuir films or vesicles for the development of PDA sensor films or other applications such as nonlinear optics and field-effect transistors are not known, so the polymer contents cannot be deduced from experimental spectra. Here we introduce a novel method, using nuclear reaction analysis (NRA), that allows a quantitative determination of the polymer content X proportion of monomers that have been incorporated into PDA chains. We apply it to pentacosadiynoic acid (PCDA) evaporated microcrystalline films.