Resonant excited state absorption (ESA) and relaxation processes in Tb(3+)-doped aluminosilicate glasses are quantitatively evaluated. A model describing the excitation steps and upconversion emission is developed and applied to interpret the results from laser-induced surface deformation using thermal mirror spectroscopy. The fluorescence quantum efficiency of level (5)D(4) was found to be close to unity and concentration independent while, for the level (5)D(3), it decreases with Tb(3+) concentration. Emission spectroscopy measurements supported these results. ESA cross sections are found to be more than three orders of magnitude higher than the ground state absorption cross section.
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http://dx.doi.org/10.1364/OL.38.004667 | DOI Listing |
Langmuir
January 2025
Department of Chemical Engineering and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, United States.
The chemical reactivity of glass surfaces is often studied with elemental analysis techniques, and although such characterization methods provide insights on compositional changes from exposure to specific chemical conditions, molecule-specific chemical reactions are not determined unambiguously. This study demonstrates the use of reflection-absorption infrared spectroscopy (RAIRS) to detect molecular species on alkali-free boroaluminosilicate and alkali aluminosilicate glasses, using acetic acid vapor as a model reactant to probe reaction sites at the surface with or without pretreatment by aqueous solutions of varied pH. With the assistance of the theoretical calculation of spectral changes based on refractive indices of bulk materials, it was possible to identify the molecular species being removed and produced at the glass surface.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States.
In two-dimensional (2D) chiral metal-halide perovskites (MHPs), chiral organic spacers induce structural chirality and chiroptical properties in the metal-halide sublattice. This structural chirality enables reversible crystalline-glass phase transitions in (-NEA)PbBr, a prototypical chiral 2D MHP where NEA represents 1-(1-naphthyl)ethylammonium. Here, we investigate two distinct spherulite states of (-NEA)PbBr, exhibiting either radial-like or stripe-like banded patterns depending on the annealing conditions of the amorphous film.
View Article and Find Full Text PDFJ Magn Reson Imaging
January 2025
Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China.
Background: At high magnetic fields, degraded image quality due to dielectric artifacts and elevated specific absorption rate (SAR) are two technical challenges in fetal MRI.
Purpose: To assess the potential of high dielectric constant (HDC) pad in increasing image quality and decreasing SAR for 3 T fetal MRI.
Study Type: Prospective.
RSC Adv
January 2025
Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials, and Bioengineering, Kansai University Suita Osaka 564-8680 Japan
We synthesized ,-dimethylformamide (DMF)-stabilized manganese nanoparticles (Mn NPs) in a one-step process under air using manganese(ii) chloride as the precursor. The Mn NPs were characterized in terms of particle size, oxidation state, and local structure using annular dark-field scanning transmission electron microscopy (ADF-STEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). The results indicate that Mn NPs are divalent nanosized particles with Mn-O bonds.
View Article and Find Full Text PDFJ Biomed Opt
January 2025
Washington University in St. Louis, Department of Biomedical Engineering, St. Louis, Missouri, United States.
Significance: Existing photoacoustic phantoms are unable to mimic complex microvascular structures with varying sizes and distributions. A suitable material with structures that mimic intricate microvascular networks is needed.
Aim: Our aim is to introduce loofah as a natural phantom material with complex fiber networks ranging from 50 to , enabling the fabrication of phantoms with controlled optical properties comparable to those of human microvasculature.
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