Transformations in In-MoO 3 nanosystems have been studied by optical spectroscopy, micros copy, and gravimetry in relation to the thickness of the In and MoO 3 layers and heat treatment temperature and time. We have measured the contact potential difference across the In and MoO 3 films and the photo voltage in the In-MoO 3 system and constructed the energy band diagram of the In-MoO 3 system. A model has been proposed for the thermal transformation of the MoO 3 films in In-MoO 3 bilayers, which involves a redistribution of equilibrium charge carriers at the contact, the formation of a [(V a ) ++ e] center during the preparation of the MoO 3 film, transformation of the center into a [e(V a ) ++ e] center during the fabrication of the In-MoO 3 bilayer, and thermal ionization of the [e(V a ) ++ e] center.
Particulate matter (PM) <10 μm in size represents an extremely heterogeneous and variable group of objects that can penetrate the human respiratory tract. The present study aimed to isolate samples of coarse and ultrafine PM at some distance from polluting industries (1–1.5 km from the border of open-cast mines). PM was collected from snow samples which allowed the accumulation of a relatively large amount of ultrafine particles (UFPs) (50–60 mg) from five objects: three open-cast mines, coal power plants, and control territories. The chemical composition of PM was examined using absorption spectroscopy, luminescence spectroscopy, high-performance liquid chromatography, X-ray diffraction (XRD), and X-ray fluorescence (XRF) analyses of solid particle material samples. Toxicity was assessed in human MRC-5 lung fibroblasts after 6 h of in vitro exposure to PM samples. The absorption spectra of all the samples contained a wide non-elementary absorption band with a maximum of 270 nm. This band is usually associated with the absorption of dissolved organic matter (DOM). The X-ray fluorescence spectra of all the studied samples showed intense lines of calcium and potassium and less intense lines of silicon, sulfur, chlorine, and titanium. The proliferation of MRC-5 cells that were exposed to PM0.1 samples was significantly (p < 0.01) lower than that of MRC-5 cells exposed to PM10 at the same concentration, except for PM samples obtained from the control point. PM0.1 samples—even those that were collected from control territories—showed increased genotoxicity (micronucleus, ‰) compared to PM10. The study findings suggest that UFPs deserve special attention as a biological agent, distinct from larger PMs.
Optical spectroscopy results demonstrate that heat treatment of 2 to 60 nm thick MoO 3 films for 1 s to 120 min in the temperature range 573-873 K reduces their absorbance in the range λ = 300-480 nm (λ max = 350 nm) and increases it in the range λ = 480-1100 nm (λ max = 870 nm). The degree of conversion of the MoO 3 films increases with increasing heat treatment time and temperature and with decreasing film thickness. A mechanism is proposed for the thermal modification of MoO 3 films, which involves the forma tion of a [(V a ) ++ e] center during the preparation of the MoO 3 film and a thermally activated electron transi tion from the valence band to the level of the [(V a ) ++ e] center, resulting in the formation of an [e (V a ) ++ e] center.
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