Grupo de Optoelectrónica

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    Accuracy and Mechanistic Details of Optical Printing of Single Au and Ag Nanoparticles
    (2017-08-30) Cerrotta, Santiago; Garjiulo, Julian; Violi, Lanina; Chvatal, Lukas; Cortes, Emiliano; Perassi, Eduardo; Diaz, Fernando; Zemánek, Pavel; Stefani, Fernando D.;
    Optical printing is a powerful all-optical method that allows the incorporation of colloidal nanoparticles (NPs) onto substrates with nanometric precision. Here, we present a systematic study of the accuracy of optical printing of Au and Ag NPs, using different laser powers and wavelengths. When using light of wavelength tuned to the localized surface plasmon resonance (LSPR) of the NPs, the accuracy improves as the laser power is reduced, whereas for wavelengths off the LSPR, the accuracy is independent of the laser power. Complementary studies of the printing times of the NPs reveal the roles of Brownian and deterministic motion. Calculated trajectories of the NPs, taking into account the interplay between optical forces, electrostatic forces, and Brownian motion, allowed us to rationalize the experimental results and gain a detailed insight into the mechanism of the printing process. A clear framework is laid out for future optimizations of optical printing and optical manipulation of NPs near substrates.
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    Room evacuation through two contiguous exits
    (Physica A: Statistical Mechanics and its Applications, 2017-05-15) Sticco, Ignacio; Frank, Guillermo; Cerrotta, Santiago; Dorso, Claudio
    Current regulations demand that at least two exits should be available for a safe evacuation during a panic situation. Although the "faster is slower" effect is expected to take place near the exits, the evacuation time will improve because of the additional exits. However, rooms having contiguous doors not always reduce the leaving time as expected. We investigated the relation between the doors separation and the evacuation performance. We found that there exists a separation distance range that does not really improve the evacuation time, or it can even worsen the process performance. To our knowledge, no attention has been given to this issue in the literature. This work reports how the pedestrians dynamics differ when the separation distance between two exit doors changes and how this affects the overall performance.