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The design of a new electrochromic display based on Langmuir-Blodgett (LB) films of the praseodymium bisphthalocyanine complex is reported. In situ UV-VIS spectra of the display show four colour changes, blue-+green-+yellowish -+red, when a potential ranging from -2 to + 2 V is applied. The device retains its colouration under open-circuit conditions.After lo5 cycles no significative changes are observed in the spectra. The device remains in the red form at open circuit for six months, and can be cycled again 1 O3 times without significative modification of its behaviour.

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Langmuir-Blodgett (LB) films of two new asymmetrically substituted phenylbisphthalocyanines, tetra-3,4,5,6-phenyllutetium bisphthalocyanine (PcLuPc4") and tetra-3,4,5,6-phenyl-tetra-3',4',5',6'-phenyllutetium bisphthalocyanine ( P C~~~L~P C~~) have been prepared.The spectroscopic studies include UV-vis, FTIR, and surface-enhanced Raman scattering (SERS) techniques. Electrochromism in LB films, formed on I T 0 glass, was observed with a n electrode potential ranging from -0.4 to +1.2 V in 0.1 M KC104 aqueous solution. Similar color changes were observed after chemical oxidation-reduction and acid-base treatment.The presence of substituents and the lowering of the symmetry when compared to the parent compound LuPc2, increases the number of IR-active modes particularly in the 600-780 cm-' region. The interaction of the LB films with NO, was followed using SERS on gold islands substrates.

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Semiconductor nanowires (NWs) are the building blocks of future nanoelectronic devices. Furthermore, their large refractive index and reduced dimension make them suitable for nanophotonics. The study of the interaction between nanowires and visible light reveals resonances that promise light absorption/scattering engineering for photonic applications. Micro-Raman spectroscopy has been used as a characterization tool for semiconductor nanowires. The light/nanowire interaction can be experimentally assessed through the micro-Raman spectra of individual nanowires. As compared to both metallic and dielectric nanowires, semiconductor nanowires add additional tools for photon engineering. In particular, one can grow heterostructured nanowires, both axial and radial, and also one could modulate the doping level and the surface condition among other factors than can affect the light/NW interaction. We present herein a study of the optical response of group IV semiconductor nanowires to visible photons. The study is experimentally carried out through micro-Raman spectroscopy of different group IV nanowires, both homogeneous and axially heterostructured (SiGe/Si). The results are analyzed in terms of the electromagnetic modelling of the light/nanowire interaction using finite element methods. The presence of axial heterostructures is shown to produce electromagnetic resonances promising new photon engineering capabilities of semiconductor nanowires.