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The enhanced transmission through periodic arrays of sub-wavelength holes in optically-thick metallic films has many potential applications, such as in wavelength filters, light extraction from light emission diodes, and subwavelength photolithography. A color filter comprising arrays of subwavelength holes in an aluminum film has been fabricated. In addition to the simplicity of the process, the aluminum film enables the excitation of visible-range surface plasmons due to its high plasma frequency. Periodic nanostructures in the aluminum film open the way for new visible color filters.

The light-induced and tip-induced polymerization of two diacetylene derivatives has been investigated at the air/solid interface by scanning tunneling microscopy (STM). One molecule is an isophthalic acid derivative with one diacetylene group, while the other one, a terephthalic acid derivative, contains two diacetylene functions. The design of the molecules (symmetry, presence of alkyl chains and hydrogen bonding moieties) leads to the formation of highly ordered two-dimensional patterns where the diacetylene groups stack in an optimal fashion. Both diacetylene derivatives can be polymerized by UV light irradiation, and locally the polymerization can be initiated and controlled by the STM tip. In addition to the formation of one-dimensional organic structures, it was possible to create two-dimensional organic nanostructures.

Plastic crystals represent a unique compound class that is often encountered in molecules with globular structures. The highly symmetric cubic crystal structure of plastic crystals endows these materials with multiaxial ferroelectricity that allows a three-dimensional realignment of the polarization axes of the crystals, which cannot be achieved using conventional molecular ferroelectric crystals with low crystal symmetry. In this work, we focused our attention on malleability as another characteristic feature of plastic crystals. We have synthesized the new plastic/ferroelectric ionic crystals tetramethylammonium tetrachloroferrate(III) and tetramethylammonium bromotrichloroferrate(III), and discovered that free-standing translucent films can be easily prepared by pressing powdered samples of these compounds. The thus obtained polycrystalline films exhibit ferroelectric polarization switching and a relatively large piezoelectric response at room temperature. The ready availability of functional films demonstrates the practical utility of such plastic/ferroelectric crystals, and considering the vast variety of possible constituent cations and anions, a wide range of applications should be expected for these unique and attractive functional materials.