ABSTRACT
Future space missions will operate in increasingly hostile environments, such as those in low-perihelion solar orbits and Jovian magnetosphere. This exploration involves the selection of optical materials and components resistant to the environmental agents. The conditions in space are reproduced on ground through the use of ion accelerators. The effects of He particles coming from the solar wind impinging on a gold thin film have been systematically investigated, considering absorbed doses compatible with the duration of the European Space Agency Solar Orbiter mission. Structural and morphological changes have been proved to be dependent not only on the dose but also on the irradiation flux. A predictive model of the variation of thin film reflectance has been developed for the case of lower flux irradiation. The results are discussed regarding reliability and limitations of laboratory testing. The outcomes are important to address the procedures for the space qualification tests of optical coatings.
ABSTRACT
Strongly (001) oriented BiOCl nanoflakes have been prepared at room temperature by the controlled hydrolysis of bismuth chloride in the presence of acetylacetone. The nanoflakes thermally treated in air up to 600 °C have been studied by X-Ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Composition, structure and morphology of the nanoflakes have been correlated to their electronic absorption and luminescence properties. Irrespective of the thermal treatments, the samples are characterized by transmittance higher than 98% in the near-infrared region. In the mildly annealed specimen (≤ 200 °C), the absorption bands in the ultraviolet can be effectively exploited for the selective excitation of the blue (394 nm) and green (520 nm) photoluminescence, the latter being visible only for λ(exc) > 310 nm. Conversely, at higher temperature only the blue emission is observed which, on the basis of the observed trend, can be assigned to emitting centres located in the oxide sheet of the Bi-O-Cl stacks.
ABSTRACT
The oligomerization of Sn(OBu(t))(4) in the sol-gel process has been studied by several different analytical approaches. Electrospray ionization (ESI) mass spectrometry was highly effective in describing the first species produced by the hydrolysis-polycondensation reactions. Mössbauer spectroscopy has elucidated the fast behavior of the hydrolytic oligomerization process, while calorimetric data have demonstrated the high enthalpy of the reaction in the presence of different solvents.
Subject(s)
Organotin Compounds/chemistry , Spectrometry, Mass, Electrospray Ionization/methods , Air Pollutants/analysis , Air Pollutants/chemistry , Calorimetry , Hydrolysis , Organotin Compounds/analysis , Spectroscopy, MossbauerABSTRACT
The polycondensation of Ti(O-i-C3H7)4 (1) and Ti(O-n-C4H9)4 (2), precursors widely employed in sol-gel processes, has been investigated by electrospray ionization mass spectrometry. By analysis of 10(-6) M methanol solutions of compounds 1 and 2, the same ionic species are detected, proving that the first step in the polycondensation reaction is the i-propyl (or n-butyl) alcohol-methanol complete exchange. This reaction leads to the Ti(OCH3)4 (3) species, representing the synthon of the polycondensation. Various oligomers of 3 have been detected and characterized by MS/MS experiments, and the related mechanisms have been discussed. A minor oligomeric series due to hydroxyl-containing polycondensation products has also been characterized.
ABSTRACT
In the crystal of the title compound, C(10)H(12)O(2), there are two symmetry-independent molecules, which are essentially superimposable. Each molecule exhibits an intramolecular O-H.O hydrogen bond, with O.O separations of 2.483 (4) and 2.468 (4) A.
