In this paper, an optical method of measuring the mass density of polarizable gases is proposed using a plasmonic refractive index nano-sensor. Plasmonic sensors can detect very small changes in the refracting index of arbitrary dielectric materials. However, attributing them to a specific application needs more elaboration of the material's refractive index unit's (RIU) relation with the introduced application. In a gaseous medium, the optical properties of molecules are related to their dipole moment polarizability. Hence, the theoretical index-density relation of Lorentz-Lorenz is applied in the proposed sensing mechanism to interpret changes in the gas' refractive index and to changes in its density. The proposed plasmonic mass density sensor shows a sensitivity of 348.8nm/(gr/cm) for methane gas in the visible light region. This sensor can be integrated with photonic circuits for gas sensing purposes.
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http://dx.doi.org/10.1364/AO.457454 | DOI Listing |
J Mol Model
January 2025
Department of Chemistry, Military Institute of Engineering, Praça General Tibúrcio 80, Rio de Janeiro, Brazil.
Context: Nitrocellulose, widely used in energetic materials, is prone to thermal and chemical degradation, compromising safety and performance. Stabilizers are molecules used in the composition of nitrocellulose-based propellants to inhibit the autocatalytic degradation process that produces nitrous gases and free nitric acids. Curcumin, (1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, known for its antioxidant properties and a potential green stabilizer, was investigated using Density Functional Theory (DFT) focusing on its interaction with nitrogen dioxide.
View Article and Find Full Text PDFHeliyon
November 2024
Department of Physics & Astronomy, University College London, WC1E 6BT, London, UK.
We describe a new optical diagnostic for determining the composition of gases by measuring the motion of atoms and molecules trapped within very deep optical lattices. This non-resonant method is analogous to conventional Raman scattering, except that the observed spectral features relate to the oscillatory center-of-mass motion of each species within the lattice, determined uniquely by their respective polarizability-to-mass ratio. Depending on the density of the probed sample, detection occurs either via optical scattering at the high end or via non-resonant ionization at the lower end.
View Article and Find Full Text PDFLangmuir
November 2024
Division of Energy, Matter and Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, Missouri 64110, United States.
Selective adsorptive capture and separation of chemically inert krypton (Kr) and xenon (Xe) noble gases with very low ppmv concentrations in air and industrial off-gases constitute an important technological challenge. Here, using a synergistic combination of experiment and theory, the microporous crystalline vanadomolybdates (MoVO) as highly selective Kr sorbents are studied in detail. By varying the Mo/V ratios, we show for the first time that their one-dimensional (1D) pores can be fine-tuned for the size-selective adsorption of Kr over the larger Xe with selectivities reaching >100.
View Article and Find Full Text PDFJ Chem Phys
June 2024
Institute of Ion Physics and Applied Physics, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria.
High-accuracy molecular force field models suited for hot gases and plasmas are not as abundant as those geared toward ambient pressure and temperature conditions. Here, we present an improved version of our previous electron-density based force field model that can now account for polarization effects by adjusting the atomic valence electron contributions to match ab initio calculated Mulliken partial charges. Using a slightly modified version of the Hohenberg-Kohn theorem, we also include an improved theoretical formulation of our model when applied to systems with degenerate ground states.
View Article and Find Full Text PDFSci Rep
June 2024
Departamento de Fisica y Geociencias, Universidad del Norte, km 5 Via Puerto Colombia, Barranquilla, Colombia.
Ab initio calculations in forsterite (Mg SiO ) are used to gain insight into the formation of point defects and incorporation of noble gases. We calculate the enthalpies of incorporation both at pre-existing vacancies in symmetrically non-equivalent sites, and at interstitial positions. At high pressure, most structural changes affect the MgO units and the enthalpies of point defects increase, with those involving Mg and Si vacancies increasing more than those involving O sites.
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