Self-assembled atomic chains can be triggered at stepped Si(111) surfaces by adding sub-monolayer amounts of metals, such as gold, silver, platinum, alkali metals, alkaline earths, and rare earths. A common feature of all these structures is the honeycomb chain, a graphitic strip of Si atoms at the step edge that is lattice matched in the direction parallel to the edge but completely mismatched...

In silicon-based solar cells, a substantial part of the energy losses is related to the charge carriers thermalization in the UV-blue range and the week carriers collection at these wavelenghts. To avoid this issue, we introduce a new concept which combines a rare-earths doped thin layer with a photonic crystal (PC) layer, allowing an efficient conversion from UV-blue photons to near-IR photons...

The temperature dependence of the rare-earth valence bands has been regarded as a realization of the Stoner behavior. The exchange splitting of the electronic states appears to scale as the magnetic order parameter for T<T(C) and to vanish at T = T(C). We report here a spin-resolved photoemission study on the evolution of Gd bulk bands for 0.5< or =T/T(C)< or=1. The spin-polarized spectral line...

The laser-induced luminescence studies of the rare earth titanates (R2Ti2O7) (R=La, Nd and Gd) using 355 nm radiation from an Nd:YAG laser are presented. These samples with submicron or nanometer size are prepared by the self-propagating high temperature synthesis (SHS) method and there is no known fluorescence shown by these rare earths in the visible region. Hence, the luminescence transition...

Reaction of N-phenyl-pivalohydroxamic acid with Ce(III) precursors leads to a homoleptic hydroxamate complex: Ce(IV)[(t)BuC(O)N(O)Ph]4. Electrochemical experiments indicate a significant stabilization of the Ce(IV) cation at Ep,c = -1.20 V versus SCE in the hydroxamate ligand framework. The spontaneous oxidation of Ce(III) in a hydroxamate ligand field is discussed in the context of beneficiati...

The validity of using rare earth elements as flow markers of undigested residues was evaluated by comparing mean gastrointestinal residence time (GMRT) of rare earths specifically applied to cottonseed hulls (CSH) to that of the indigestible fiber of CSH. Feces were collected from five lambs fed a mineral supplemented diet of CSH containing 52 g CP/kg DM and five lambs fed a CSH plus cottonseed...