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We have experimentally and theoretically developed a unique thermally stimulated midinfrared source that emits radiation within a narrow range of wavelengths (δλ/λ⩽0.2). The emission wavelengths are defined by the periodicity of a metal coated silicon–air photonic crystal etched into the emitter surface. The lattice of the holes in the metal mediate the coupling of light into discrete surface plasmon states. This yields surfaces with spectrally nonuniform infrared reflection properties where over much of the IR 90+% of photons are reflected yet, in a narrow spectral region, 90% absorption is observed. Transfer matrix calculations simulate well the position and strength of the absorption features. This technology will afford tunable infrared emitters with high power in a narrow spectral band that are critical for sensing, spectroscopy, and thermophotovoltaic applications.

In a reaction proceeding within a nanoscopic volume, supramolecular clusters were transformed to polymer objects while retaining their shape and size. Spatial isolation of the cross-linkable blocks of oligobutadiene that were involved in this stitching reaction was achieved by self-assembly of the molecules that made up the clusters. Thermal activation of cross-linking yielded macromolecules (molecular weight of 70,000) with a narrow size distribution that was similar to that of the supramolecular clusters. The macromolecules obtained have an anisotropic shape (2 nanometers by 8 nanometers), as determined by electron microscopy and small-angle x-ray scattering, and form materials that exhibit a liquid crystalline state.

We report here on the synthesis and characterization of several triblock rodcoil molecules containing conformationally rigid and flexible sequences and luminescent chromophores based on phenylene vinylene. The molecules consist of blocks of oligostyrene, oligoisoprene, and a rigid rod block. The synthesis of the rod blocks required the preparation of new phenylene vinylene oligomers. On the basis of electron microscopy and X-ray diffraction experiments, these systems were found to self-organize into supramolecular nanostructures which in turn assemble into monolayers. The nanostructures have diameters between 3.5 and 5 nm, and the regularity of the nanostructures depends on rod-to-coil volume fraction. The layer spacing of one system is 6.0 nm when cast from solution but increases to 7.8 nm upon annealing at 150 °C, possibly as a result of an increase in aggregation number. Interestingly, the formation of supramolecular nanostructures and the observed hierarchical order in the materials formed by rodcoil molecules can be completely suppressed by lowering the rod-to-coil volume ratio. When the chemical structure of rod segments is changed, the nanostructures formed can undergo a drastic increase in aspect ratio. These changes in shape maybe linked to different tendencies for aggregation among rod segments. Absorption and emission spectra of supramolecular solids are similar to dilute solution spectra and different from those of similar disordered materials.