RESUMO

Peat, an organic compound easily found in the soil (easy to acquire), has more than 50% elemental carbon in its composition and can be used as raw material to produce carbon quantum dots (CQDs, C-dots, Carbon Dots). In this work we describe two simple and low-cost routes for the acquisition of these photoluminescent materials based on peat. The final products were characterized by Fourier transform infrared spectroscopy (FTIR), absorption (UV-Vis) and emission (PL) spectra and high-resolution transmission electron microscopy (HRTEM). The produced CQDs have an average size of 3.5 nm and exhibit coloration between blue and green. In addition, it is possible to produce photoluminescence by means of the aromatic compounds also present in the composition of the peat, in turn exhibiting an intense green coloration. The results indicate great versatility of peat for the production of photoluminescent materials.

RESUMO

We present an extensive study of the optical properties of Myrcia sylvatica essential oil with the goal of investigating the suitability of its material system for uses in organic photovoltaics. The methods of extraction, experimental analysis, and theoretical modeling are described in detail. The precise composition of the oil in our samples is determined via gas chromatography, mass spectrometry, and X-ray scattering techniques. The measurements indicate that, indeed, the material system of Myrcia sylvatica essential oil may be successfully employed for the design of organic photovoltaic devices. The optical absorption of the molecules that compose the oil are calculated using time-dependent density functional theory and used to explain the measured UV-Vis spectra of the oil. We show that it is sufficient to consider the α-bisabolol/cadalene pair, two of the main constituents of the oil, to obtain the main features of the UV-Vis spectra. This finding is of importance for future works that aim to use Myrcia sylvatica essential oil as a photovoltaic material.

Assuntos

Myrtaceae/química , Óleos Voláteis/química , Cromatografia Gasosa , Espectrometria de Massas , Difração de Raios X

RESUMO

This work presents a detailed study concerning the quantum isotope effects on the H+Li[Formula: see text] reaction, when the hydrogen is replaced by muonium, deuterium, and tritium. To verify such effects on these isotope reactions, it was applied an accurate time-independent quantum scattering approach to determine the dynamic properties, such as state-to-state probabilities as a function of the total energy, the product energetic distribution, and the contribution of the ro-vibrational excitation on the reaction probabilities. From the obtained results, it was possible to observe a significant increase on the promotion of the H+Li2 reaction when hydrogen is replaced by tritium. This fact shows the importance of the isotopic substitution in the making and breaking of the chemical bonds in the reactive systems.