arXiv subjects

A. Chavarría-Sibaja

Publications and source records attributed to A. Chavarría-Sibaja.

4 recordsLinked to original sources

arXiv2021

MgO surface lattice phonons observation during Interstellar ice transition

Relevant information on the origins of the solar system and the early evolution of life itself can be derive from systematic and controlled exploration of amorphous water ice here on Earth. Therefore, over the last decades, a huge effort on experimental methodologies has been made to study the multiple crystal ice phases, which are observed outside our home-gravitational-potential. By employing (100)-oriented MgO lattice surface as a microcantilever sensor, we conducted the first ever study on the dynamics of the Structural Phase Transition at 185 K in amorphous water ice by means of coherent elastic scattering of electron diffraction. We estimate the amount of phonons caused by this transition applying precise quantum computing key tools, resulting in a maximum value of 1.23 $\pm$ 0.02. Further applications of our microcantilever sensor were assessed using unambiguous mapping of the surface stress induced by the c(4$\times$2) $\longleftrightarrow$ p(3$\times$2) Structural Phase Transition of the interstellar ice formulated on the Williamsom-Hall model. This development paves the way and thus establishes an efficient characterization tool of the surface mechanical strains of materials with potential applications arising from interstellar ice inclusive glaciers to the wide spectrum of solid-state physics.

cond-mat.mtrl-sci↗

arXiv2021

Revealing time's secrets at the National Theatre of Costa Rica: innovative software for cultural heritage research

Establishing affordable, efficient, accessible, innovative, and multidisciplinary methodologies are key to the creation of modern public policies on cultural heritage. Limited access to large-format paintings is a challenge to restoration scientists seeking to obtain information quickly, in a non-invasive manner, and identify regions of interest. Therefore, we put forward two unique software tools based on multispectral imaging techniques, with the long-term aim of assessing the artist's intentions, creative process, and color palette. This development paves the way for a comprehensive and multidisciplinary understanding of the mysteries encompassed in each pictorial layer, through the study of their physical and chemical characteristics. We conducted the first-ever study on Musas I and II, two large-format paintings by Italian artist Carlo Ferrario, located in the National Theatre of Costa Rica. In this study, we used our novel techniques to chose regions of interest in order to study sample layers; while also assessing the works' state of conservation and possible biodeterioration. We explored the applications of our two versatile software tools, RegionOfInterest and CrystalDistribution, and confirmed paint stratigraphies by means of microscopy and spectroscopy analyses. In a pilot study, we identified the artist's main color palette: zinc white, lead white, chrome yellow, lead read, viridian, along with artificial vermilion and ultramarine pigments. We were able to identify artificial vermilion and ultramarine and distinguish them from the natural pigments using CrystalDistribution to map the average size and diameter of the pigment crystals within the paint layers. This study demonstrated that software-based multidisciplinary imaging techniques are fundamental in establishing preventive and non-invasive methods for historical painting conservation studies and virtual restoration.

physics.app-ph↗

arXiv2021

Continuous slowing of a gadolinium atomic beam

The article presents the development of a new and innovative experimental method to fully characterize a solenoidal "spin-flip" Zeeman slower (ZS) using a Quartz Crystal $μ$-balance (QCM) as a kinetic energy sensor. In this experiment, we focus a 447.1 nm laser into a counter-propagating beam of gadolinium (Gd) atoms in order to drive the dipole transition between ground $^{9}$D$^{0}_{2}$ state and $^{9}$D$_{3}$ excited state. The changes in the velocity of the beam were measured using a QCM during this process, as a novel and alternative method to characterize the efficiency of a 1 m-long spin-flip Zeeman slower. The QCM, normally used in solid-state physics, is continuously and carefully monitored to determine the change in its natural frequency of oscillation. These changes reveal a direct relation with changes in the deposition rate and the momentum exchanged between the QCM and Gd atoms. Hence, in terms of ultracold atom physics, it might be used to study the time-evolution of the velocity distribution of the atoms during the cooling process. By this method, we obtain a maximum atom average velocity reduction of (43.5 $\pm$ 6.4)$\%$ produced by our apparatus. Moreover, we estimate an experimental lifetime of $τ_{e}$ = 8.2 ns for the used electronic transition, and then we compared it with the reported lifetime for 443.06 nm and 451.96 nm electronic transitions of Gd. These results confirm that the QCM offers an accessible and simple solution to take into account for laser cooling experiments. Therefore, a novel and innovative technique can be available for future experiments.

physics.atom-ph↗

arXiv2015

Detection of the adsorption of water monolayers through the ion oscillation frequency in the magnesium oxide lattice by means of Low Energy Electron Diffraction

We investigate the variation of the oscillation frequency of the Mg$^{2+}$ and O$^{2-}$ ions in the magnesium oxide lattice due to the interactions of the surface with water monolayers by means of Low Energy Electron Diffraction. Our key result is a new technique to determine the adsorbate vibrations produced by the water monolayers on the surface lattice as a consequence of their change in the surface Debye temperature and its chemical shift. The latter was systematically investigated for different annealing times and for a constant external thermal perturbation in the range of 110-300 K in order to accomplish adsorption or desorption of water monolayers in the surface lattice.

cond-mat.mtrl-sci↗