The low-field conductivity of zeolite-encapsulated molecular wires

The first measurements of an upper bound for the low-field conductivity of a molecular wire are presented here. We were able to encapsulate polypyrrole with chain lengths more than 10 monomers within the channels of different zeolites. Although the chains are fully oxidized by intrazeolite Fe3 + ions, and should conduct (when included in a bulk polymer), they do not exhibit, in the zeolite, significant ac conductivity up to 1 GHz. This suggests that other strategies than low field conductivity are needed to inject charges and transmit information through isolated molecular wires

Life in the Atacama — Year 2: Geologic reconnaissance through long-range roving and implications on the search for life

The Life in the Atacama-2004 project, which included geological, morphological, and mineralogical mapping through combined satellite, field-based, and microscopic perspectives and long-range roving, led to the localization of potential habitats

Spectroscopic results from the Life in the Atacama (LITA) project 2004 field season

Analysis of spectroscopy datasets from rover field tests in the Atacama Desert (Chile), focusing on the composition of the surface and identification of potential habitats for life

STABILITY OF THE MAGNETIC POLARON

On étudie la stabilité du polaron magnétique dans un semiconducteur ferromagnétique à bande large. Utilisant la méthode des fonctions de Green on développe les équations de mouvement aux systèmes électroniques et magnétiques jusqu'à deuxième ordre en constante du couplage d'échange. On trouve que dans les chalcogénes de Eu le polaron est stable dans une région relativement large au voisinage de TC.The stability of the magnetic polaron is studied in a broad band ferromagnetic semiconductor. Using the Green's function techniques the equations of motion for the electronic and magnetic systems are developed up to second order in the exchange coupling constant. It is found that in Eu chalcogenides the polaron is stable in a relatively broad region around TC

Light-emitting diodes of poly (3-hexylthiophene) Langmuir-Blodgett films

Poly(3-hexylthiophene) Langmuir-Blodgett films have been used as emitting layers in light-emitting diodes. The effect of the film thickness and additional carrier-transport layers on current-voltage characteristics and quantum efficiency were studied, and the electroluminescence spectra measured. Hole transporting poly(9-vinylcarbazole) was used both as a separate layer in a heterostructure device and in a blend with emitting material. The electron-transport material 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole was used in a blend with the emitting material. The connections between the diode structure and the electro-optical properties as well as operation mechanisms are discussed