The RADMED monitoring program as a tool for MSFD implementation: toward an ecosystem based approach

In the western Mediterranean Sea, the RADMED monitoring programme is already conducting several of the evaluations required under the Marine Strategy Framework Directive (MFSD) along the Spanish Mediterranean coast. The different aspects of the ecosystem that are regularly sampled under this monitoring programme are the physical environment and the chemical and biological variables of the water column, together with the planktonic communities, biomass and structure. Moreover, determinations of some anthropogenic stressors on the marine environment, such as contaminants and microplastics, are under development. Data are managed and stored at the Instituto Español de Oceanografía (IEO) Data Centre that works under the Sea- DataNet infrastructure, and are also stored in the IBAMar database. In combination with remote sensing data, they are used to address open questions on the ecosystems in the western Mediterranean Sea.Postprint2,293

Optical properties of nanometric TiO2 clusters deposited on thin films by high pressure sputtering

Titanium dioxide thin films have been prepared by using a magnetron sputtering source placed inside a high pressure aggregation chamber. This preparation technique allows the production of fine particles from a target material through sputtering after cluster aggregation inside a high pressure (10- 1 mbar) He/Ar gas atmosphere. After that process, by channelling the clusters to a low pressure main deposition chamber, it is possible to prepare films made up by nanometric clusters. The distribution of the cluster size can be changed controlling the residence time within the aggregation zone. Films of clusters with different sizes have been deposited after varying the Ar/He atmosphere ratio and its pressure in the aggregation region. Cluster size distribution has been characterized by Atomic Force Microscopy as a function of different preparation parameters. Finally, the crystalline degree, structural phase and band-gap of the titanium oxide were obtained by means of optical spectroscopies to study the size dependence of the nanometric clusters properties. © 2009 Elsevier B.V. All rights reserved.The financial support MEC though project MAT2006-01004 is acknowledged. JSM is grateful to MICINN for the financial support within the JdlC program.Peer Reviewe

Huge photoresistance in transparent and conductive indium titanium oxide films prepared by electron beam-physical vapor deposition

Transparent and conductive indium titanium oxide (ITiO) films have been obtained by electron beam physical vapour deposition with Ti content from 5 at % up to 28 at %. X-ray absorption spectroscopy techniques have been used to identify the local environment of Ti ions. Even at the lowest concentrations Ti is not incorporated into the In2O3 structure but forms clusters of a Ti-In mixed oxide that present a distorted rutile TiO2 short-range order. The optical transmittance of the annealed samples reaches 95 % and no significant variation of the gap energy (around 3.7 eV) is observed with Ti content. The electronic conductivity under light irradiation is studied evidencing a huge photo-resistance in the samples with Ti content above 22 at % reaching more than two orders of magnitude for the 26 at % Ti under illumination with few μW/cm2 at 365 nm. Hall and conductivity results are analyzed using a model that takes into account both electron and hole carriers as well as the conductivity enhancement by carrier photogeneration. The electron carrier density decreases with Ti content while its mobility increases up to values of 1000 cm2/(V s). Oxygen annealed ITiO films obtained by this technique with Ti content below 10 at % have properties adequate as transparent semiconductors and those with Ti content higher than 22 at % have exceptional photoresistive properties relevant for numerous applications. © 2014 American Chemical Society.Peer Reviewe

X-ray absorption and Mössbauer spectroscopies characterization of iron nanoclusters prepared by the gas aggregation technique

Partially oxidized iron nanoclusters have been prepared by the gas-phase aggregation technique with typical sizes of 2-3 nm. This preparation technique has been reported to obtain clusters with interesting magnetic properties such as very large exchange bias. In this paper, a sample composition study carried out by Mössbauer and X-ray absorption spectroscopies is reported. The information reached by these techniques, which is based on the iron short range order, results to be an ideal way to have a characterization of the whole sample since the obtained data are an average over a very large amount of the clusters. In addition, our results indicate the presence of ferrihydrite, which is a compound typically ignored when studying this type of systems.Peer Reviewe

Exchange bias in iron oxide nanoclusters

Iron oxide nanoclusters have been prepared by the gas-phase aggregation technique to form thin film structures with very high exchange bias values (up to 3000Oe at low temperatures). Composition has been analysed by x-ray absorption and Mössbauer spectroscopies in order to elucidate the actual origin of the observed magnetic behaviour. The formation of a metaloxide coreshell arrangement to explain the observed exchange bias has to be discarded since results show no metallic iron content and the main presence of α-Fe2O3. The observed weak ferromagnetism and exchange bias are in agreement with the obtained size of α-Fe 2O3 nanoparticles: weak ferromagnetism because of the well-known spin canting in this antiferromagnetic structure and exchange bias because of the interaction between different spin sublattice configurations promoted by the modification of iron coordination in α-Fe 2O3 nanoparticles. Moreover, the preparation method is proposed for tuning both magnetization and exchange bias values by modification of the preparation conditions of α-Fe2O3 nanoparticles, which open new possibilities in the design of new materials with required properties. © 2011 IOP Publishing Ltd.This work has been supported by the Spanish MICINN under contracts MAT2009-08786 and CSD2009-00013 and by the regional government of Madrid though contract S2009/MAT-1756. JSM and MAL-M are grateful to MICINN for the financial support within the JdlC program. We would like to thank the SpLine CRG beamline staff at ESRF for assistance during x-ray absorption experiments.Peer Reviewe