Person:
Gámez Márquez, Francisco De Asis

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First Name
Francisco De Asis
Last Name
Gámez Márquez
URI
https://hdl.handle.net/20.500.14352/80780
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
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    Building a Hofmeister-like series for the maximum in density temperature of aqueous electrolyte solutions.
    (Journal of Molecular Liquids, 2023) Gámez Márquez, Francisco De Asis; Fernández Sedano Vázquez, Lucía; Blázquez Fernández, Samuel; Troncoso, Jacobo; Vega De Las Heras, Carlos
    The temperature of the maximum in density (TMD) at room pressure is experimentally evaluated for aqueous solutions of a set of halides containing F−, Cl−, Br−, I−, Li+, Na+, K+, Rb+, Cs+ and Mg2+ at a 1 m concentration. The measurements were performed by monitoring the density- temperature profiles and tracking the temperature-dependent position of the meniscus, in a capillary glass tube. Adding salts diminishes the TMD of the solutions with respect to pure water, being the magnitude of the change dependent on the nature of the electrolyte. The experimental values of the shift in the TMD can be split into individual ion contributions. From this information we were able to establish a rank of ions (i.e. a Hofmeister-like series) according to their efficiency in shifting down the TMD. The experimental results are also compared to simulation values obtained via Molecular Dynamics using the Madrid-2019 force field that assigns non-integer charges for the ions and is parametrized for the TIP4P/2005 water model. Finally, since the TMD is a fingerprint property of water, we will discuss the impact of ions on this maximum in relation with the way different ions modify the structure of water.
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    Light-to-Heat Conversion of Optically Trapped Hot Brownian Particles
    (ACS Nano, 2023) Ortiz Rivero, Elisa; Orozco Barrera,Sergio; Chatterjee, Hirak; Caro, Carlos; González Gómez, Carlos David; García Martín, María Luisa; Haro González, Patricia; Rica, Raúl A.; Gámez Márquez, Francisco De Asis
    Anisotropic hybrid nanostructures stand out as promising therapeutic agents in photothermal conversion-based treatments. Accordingly, understanding local heat generation mediated by light-to-heat conversion of absorbing multicomponent nanoparticles at the single-particle level has forthwith become a subject of broad and current interest. Nonetheless, evaluating reliable temperature profiles around a single trapped nanoparticle is challenging from all of the experimental, computational, and fundamental viewpoints. Committed to filling this gap, the heat generation of an anisotropic hybrid nanostructure is explored by means of two different experimental approaches from which the local temperature is measured in a direct or indirect way, all in the context of hot Brownian motion theory. The results were compared with analytical results supported by the numerical computation of the wavelength-dependent absorption efficiencies in the discrete dipole approximation for scattering calculations, which has been extended to inhomogeneous nanostructures. Overall, we provide a consistent and comprehensive view of the heat generation in optical traps of highly absorbing particles from the viewpoint of the hot Brownian motion theory.