A "quick look" at ultrafast ablation using fs-resolved phase-change microscopy

A pump-probe phase-change microscope with fs temporal resolution has been used to understand the transformation induced in the sample surface as a consequence of laser-matter interaction.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Insights on the acting role of Martian atmosphere in the fragmentation pathways of organic and C-containing inorganic compounds using LIBS

In the present work, a preliminary fundamental study about the influence of background gas in Martian surface conditions (CO2, P=7 mbar) on the formation of emitting species in laser-induced plasmas of ablated C-containing compounds was performed. Results were compared with those obtained using ambient air as surrounding gas of irradiated samples. Energy thresholds were evaluated for excited atomic and molecular species of interest resulting in the plasma using a home-made LIBS system coupled to a pressure chamber for simulating Martian environment during the analysis of samples. Inorganic salts as calcium carbonate and magnesium carbonate besides pyrene as organic reference compound were analyzed in order to discern the origin of C-containing species coexisting in the plasma plume (C, C2 and CN, mainly). Results from acquired emission spectra shed light on the different carbon sources of emitting species as a function of energetic and pressure conditions.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Femtosecond time-resolved phase-change microscopy and ablation threshold calculations to understand ultrafast laser ablation

El trabajo recoge experimentos realizados en una configuración sonda-prueba haciendo uso de un láser de femtosegundos, con el objetivo de comprender los fenómenos de ablación de materiales sólidos ras irradiación con láseres de pulso ultracorto.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Observation and modeling of interrupted pattern coarsening: surface nanostructuring by ion erosion

4 pages, 3 figures.-- PACS nrs.: 68.35.Ct, 05.45.-a, 79.20.Rf, 81.16.Rf.We report the experimental observation of interrupted coarsening for surface self-organized nanostructuring by ion erosion. Analysis of the target surface by atomic force microscopy allows us to describe quantitatively this intriguing type of pattern dynamics through a continuum equation put forward in different contexts across a wide range of length scales. The ensuing predictions can thus be consistently extended to other experimental conditions in our system. Our results illustrate the occurrence of nonequilibrium systems in which pattern formation, coarsening, and kinetic roughening appear, each of these behaviors being associated with its own spatiotemporal range.This work has been supported by Grant Nos. CSD2008-0023, CSD2007-00010, and FIS2009-12964- C05-01, -04 (MICINN, Spain), and CCG08-CSIC/MAT- 3457 (CAM, Spain).Publicad

Temporal evolution of surfaces on materials after femtosecond laser irradiation: The earliest stages (Oral presentation)

Ablation using femtosecond lasers exhibits significant differences in comparison with the nanosecond timescales. Ultrashort laser-matter interaction provides the observation of different phenomena as there is neither laser-plasma interaction nor shielding, which makes remarkable the comprehension of these fundamental processes for improving analytical results. By the design and evaluation of a time-resolved microscope with a time resolution of less than 200 fs it is possible to develop a study focused on the associated processes during the earliest stages of laser ablation on several materials, attending to their nature as semiconductors, metals or insulators. The combination of this set up with an energy-resolved study applying energies above and below the plasma threshold of materials let us establish which are the physical and chemical parameters involved in plasma generation produced by lasers.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Searching for Biosignatures in Mars by LIBS Molecular Signals Discernment

In the present study, LIBS analysis of a set of six selected molecules related to organic biosignatures -or their degradation compounds- have been carried out in both simulated Martian atmosphere and air in order to identify and discriminate them on the basis of their molecular emission features. This strategy can reveal insights into how different emission spectral modes react to changes in atmospheric conditions and therefore can help to detect those species which are more sensitive to changes in pressure and composition of the atmosphere. At high laser irradiance, atomization of organic compounds is essentially complete, although at sufficiently delayed integration times, the formation of new molecules by recombination processes can be noticed[1]. Molecular species characteristic of organic emissions such as C2, CN, NH, OH and CH were studied. Results can contribute to establish the optimal conditions for the observation of organic carbon species in laser-induced plasmas and the bases for the ensuing detection of organic biosignatures in analogous geological materials from Mars. Likewise, this research is aimed at providing a tool in the interpretation of LIBS data though the application of adapted data processing algorithms for the identification and discernment of suspected compounds of organic nature[2] [1] T. Delgado, L. García-Gómez, L. M. Cabalín, J. J. Laserna, Investigation on the origin of molecular emissions in laser-induced breakdown spectroscopy under Mars-like atmospheric conditions of isotope-labeled compounds of interest in astrobiology, Spectrochim. Acta Part B (2021) 179-106114. [2] T. Delgado, L. García-Gómez, L. M. Cabalín, J. J. Laserna, Detectability and discrimination of biomarker organic precursors in a low pressure CO2 atmosphere by LIBS, J. Anal. At. Spectrom. (2020) 35:1947.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Efficient symmetrical electrodes based on LaCrO3 via microstructural engineering.

Novel nanostructured electrodes, La0.98Cr0.75B0.25O3δ (B = Mn, Fe, Ti and Cu), are prepared by a single spraypyrolysis deposition method directly on the electrolyte and a porous Ce0.9Gd0.1O1.95 (CGO) scaffold. These perovskite-type electrodes without alkaline-earth metals exhibit low ionic/electronic conductivity; however, the polarization resistance is greatly enhanced by microstructural design. The best results are obtained for La0.98Cr0.75Mn0.25O3-δ deposited into a porous CGO-scaffold due to the synergetic effect of CGO, with high ionic conductivity, and doped-LaCrO3 with a predominantly electronic conductivity. The materials are investigated as both air and fuel electrodes for solid oxide fuel cells (SOFCs) by different structural, microstructural and electrochemical techniques. Low values of polarization resistance are achieved for nanostructured La0.98Cr0.75Mn0.25O3-δ-CGO electrodes, i.e. 0.057 Ω cm2 in air at 800 ◦C, compared to 0.96 Ω cm2 for the same powder electrode obtained by screen-printing deposition. An electrolyte-supported symmetrical cell generates a stable maximum power output of 475 mW cm 2 at 800 ◦C

Lanthanide molybdates, Ln5.4MoO11.1 (Ln = Nd, Sm and Gd), for hydrogen separation membranes

Nowadays, lanthanide molybdates (Ln6-xMoO12-, Ln = La-Lu) are attracting attention as candidates for hydrogen separation membranes due to its high ambipolar proton-electron conductivity. In these compounds, a very high degree of polymorphism is detected depending on the composition and synthesis-sintering conditions. Very recently, we carried out a comprehensive study of La5.4MoO11.1 and the effect of the synthesis temperature and cooling rate on the symmetry of the samples1. We found out that those samples suddenly cooled from 1500 ºC present a simple cubic fluorite structure, whereas those cooled at slower rates, such as 50 and 0.5 ºC min-1, present complex rhombohedral polymorphs with superstructures, denominated in that work as R1 and R2, respectively. Here, we extend this study to lanthanides smaller than lanthanum and evaluate the influence of composition and synthesis-sintering conditions on the structural and electrical properties. It was determined by X-ray diffraction that the materials are single phase after heating at 1500 ºC and cooling at different rates. Those cooled by quenching present a simple cubic fluorite structure. At lower rates, 5 and 0.5 ºC min-1, the cubic symmetry is stabilized as the size of the lanthanide decreases, as can be seen in Figure 1. XPS analysis showed the presence of Mo6+ and Mo5+ for all samples. The reduction of the cooling rate for the same composition leads to an increase of the average grain size. For a same cooling rate, the decrease of the size of the lanthanide leads to a lower average grain size. The materials are stable in very reducing conditions and the electronic conductivity increases as the size of the lanthanide becomes smaller

Membrane-disrupting iridium(III) oligocationic organometallopeptides

NOTICE: This is the peer reviewed version of the following article: Salvadó, I, Gamba, I, Montenegro J, Martínez-Costas J, Brea JM, Loza MI, Vázquez López M, Vázquez M.E. Membrane-disrupting iridium(III) oligocationic organometallopeptides. Chem. Commun., 2016,52, 11008-11011. DOI: 10.1039/C6CC05537K. This article may be used for non-commercial purposes in accordance with RSC Terms and Conditions for self-archivingA series of oligoarginine peptide derivatives containing cyclometallated iridium(III) units display remarkable cytotoxicity, comparable to that of cisplatin. In vitro studies with unilamellar vesicles support a membrane-disrupting mechanism of actionWe are thankful for the support given by the Spanish grants SAF2013-41943-R, CTQ2015-70698-R, CTQ2013-49317-EXP,CTQ2014-59646-R, and BFU2013-43513-R, and the Xunta de Galicia GRC2013-041. Support from COST Action CM1105 and the orfeo-cinqa network (CTQ2014-51912-REDC) is kindly acknowledgedS