Browsing by Author "Elgueta, S."

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    Band gap determination in multi-band-gap CuFeO2 delafossite epitaxial thin film by photoconductivity
    (2019) Vojkovic, S.; Fernandez, J.; Elgueta, S.; Vega, F. E.; Rojas, S. D.; Wheatley, R. A.; Seifert, B.; Wallentowitz, S.; Cabrera, A. L.
    The photoconductivity within a wavelength range of 450-1100 nm was determined for a sample of epitaxial delafossite CuFeO2 film grown by pulsed laser deposition. The film thickness was estimated to be 75 nm. The resistance of the films was determined with four-contact van der Pauw's method and using monochromatic illumination of the film. The most significant change in resistance resulted in three rapid lineal conductivity increases at photon energies of similar to 1.5 eV (gap-1), similar to 2.1 eV (gap-2) and similar to 2.5 eV (gap-3). The conductivity properties are well correlated with prior optical absorption results obtained in the NIR-VIS region using transmittance spectroscopy.
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    Hydrogen adsorption study on nanostructured Ag-Rh films grown by supersonic cluster beam deposition
    (2023) Vega, F.; Fernandez, J.; Elgueta, S.; Cavaliere, Emanuele; Gavioli, Luca; Cabrera, A. L.
    Following recent literature work, an interesting result on hydrogen sorption by Ag-Rh clusters was reported which do not follow the common understanding of hydrogen ab-sorption in bulk alloys. Thus, nanostructured Ag-Rh films with a composition of 75% Ag-25% Rh were grown by supersonic cluster beam deposition onto microbalance quartz crystals in order to measure hydrogen absorption. The films were exposed to H-2 gas to study hydrogen absorption at different partial pressure. The Ag-Rh films were then characterized by XPS and AFM. The Ag/Rh atomic ratio was found to be 75/25 by XPS. Surface roughness was determined by AFM to be 3 nm RMS in all the films. In disagreement with the quoted literature report, no hydrogen absorption was observed in our Ag-Rh films up to 5:3 x 10(3)Pa of hydrogen pressure. The response of the balance was checked and validated by measuring hydrogen absorption on 10 and 100 nm Pd films. The hydrogen absorption by Pd yielded an atomic H/Pd ratio of similar to 0.65 in agreement with our prior measurements.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Prioritization for liver transplantation using the MELD score in Chile : Inequities generated by MELD exceptions. A collaboration between the Chilean Liver Transplant Programs, the Public Health Institute and the National Transplant Coordinator
    (2019) Díaz, Luis Antonio; Norero, B.; Lara, B.; Robles, C.; Elgueta, S.; Humeres, R.; Poniachik, J.; Silva, G.; Wolff, R.; Innocenti, F.; Rojas, J.L.; Zapata, R.; Hunter, B.; Alvarez, S.; Cancino, A.; Ibarra, J.; Rius, M.; González Bombardiere, Sergio; Calabran, L.; Perez, R.M.