N. Garro

A Mesoporous 3D Hybrid Material with Dual Functionality for Hg2+ Detection and Adsorption

Dual-function hybrid material U1 was designed for simultaneous chromofluorogenic detection and removal of Hg(2+) in an aqueous environment. Mesoporous material UVM-7 (MCM41 type) with homogeneously distributed pores of about 2-3 nm in size, a large specific surface area exceeding 1000 m(2) g(-1), and nanoscale particles was used as an inorganic support. The mesoporous solid is decorated with thiol groups that were treated with squaraine dye III to give a 2,4-bis(4-dialkylaminophenyl)-3-hydroxy-4-alkylsulfanylcyclobut-2-enone (APC) derivative that is covalently anchored to the inorganic silica matrix. The solid was characterised by various techniques including X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and nitrogen adsorption. This hybrid solid is the chemodosimeter for Hg(2+) detection. Hg(2+) reacts with the APC fragment in U1 with release of the squaraine dye into the solution, which turns deep blue and fluoresces strongly. Naked-eye Hg(2+) detection is thus accomplished in an easy-to-use procedure. In contrast, U1 remains silent in the presence of other thiophilic transition metal ions, alkali and alkaline earth metal ions, or anions ubiquitously present in water such as chloride, carbonate, sulfate, and phosphate. Material U1 acts not only as chemodosimeter that signals the presence of Hg(2+) down to parts-per-billion concentrations, but at the same time is also an excellent adsorbent for the removal of mercury cations from aqueous solutions. The amount of adsorbed mercury ranges from 0.7 to 1.7 mmol g(-1), depending on the degree of functionalisation. In addition, hybrid material U1 can be regenerated for both sensing and removal purposes. As far as we know, U1 is the first example of a promising new class of polyfunctional hybrid supports that can be used as both remediation and alarm systems by selective signalling and removal of target species of environmental importance. Model compounds based on silica gel (G1), fumed silica (F1), and micrometre-sized MCM-41 scaffolds (M1) were also prepared and studied for comparative purposes.

Combined Raman scattering and ab initio investigation of pressure-induced structural phase transitions in the scintillator ZnWO 4

The room-temperature Raman scattering was measured in

Reduction of the internal electric field in wurtzite a-plane GaN self-assembled quantum dots

{\text{ZnWO}}_{4}

Electron-phonon interaction at the direct gap of the copper halides

up to 45 GPa. We report the pressure dependence of all the Raman-active phonons of the low-pressure wolframite phase. As pressure increases additional Raman peaks appear at 30.6 GPa due to the onset of a reversible structural phase transition to a distorted monoclinic

Effect of Impurities on Raman and Photoluminescence Spectra of AlN Bulk Crystals

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Spontaneous core–shell elemental distribution in In-rich InxGa1−xN nanowires grown by molecular beam epitaxy

-fergusonite-type phase. The low-pressure and high-pressure phases coexist from 30.6 to 36.5 GPa. In addition to the Raman measurements we also report ab initio total-energy and lattice-dynamics calculations for the two phases. These calculations helped us to determine the crystalline structure of the high-pressure phase and to assign the observed Raman modes in both the wolframite and

Effect of isotopic mass on the photoluminescence spectra of zinc oxide

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Supramolecular capping-ligand effect of lamellar silica mesostructures for the one-pot synthesis of highly dispersed ZnO nanoparticles

-fergusonite phases. Based upon the ab initio calculations we propose the occurrence of a second phase transition at 57.6 GPa from the

Optical and Vibrational Properties of Self-assembled GaN Quantum Dots

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Coherent control of resonant quantum well emission

-fergusonite phase to an orthorhombic