1,721,082 research outputs found
The optical band gap in the interpretation of the u.v.-visible absorption spectra of rich premixed flames
No full textThe optical band gap in the interpretation of the u.v.-visible absorption spectra of rich premixed flames
No full textThe optical band gap in the interpretation of the u.v.-visible absorption spectra of rich premixed flames
No full textPROPERTIES OF CARBONACEOUS NANOPARTICLES IN FLAT PREMIXED C2H4/AIR FLAMES FROM STOCHIOMETRIC C/O RATIO TO SOOT APPEARANCE LIMIT
No full textOptical properties of incipient soot
No full textThe exact knowledge of the optical properties of soot nanoparticles is fundamental for several aspects including the correct determination of the soot concentration in combustion environments using optical diagnostics and the correct estimation of the environmental impact of the emitted particles. Although extensive researches over the years have led to a substantial agreement on the optical properties of mature soot particles, the optical properties of the incipient soot nanoparticles are still uncertain. From the particle inception point to the formation of large and more mature soot particles, the evolution of the optical properties must account for variations due to the size and the physicochemical transformation of the investigated particles. This work aims to determine the refractive index and optical properties of inception particles formed in lightly sooting flames. A previous determination based on in-situ light absorption and scattering measurements is revisited taking advantage of particle size measurements by differential mobility analysis. The spectral dependencies of the optical properties are derived by the Kramers-Krӧnig analysis of the ex-situ VUV-NIR light absorption measurements. Results confirm the strong decrease in the absorptivity in the vis-NIR region of inception particles with unimodal size distribution and d63∼3 nm, and confirm a strong size dependency of soot optical properties. The thermal-optical analysis of the sampled particles shows that the particle mass absorption coefficient also correlates with organic carbon content
Particle inception in a Laminar premixed flame of benzene
No full textSpectral optical techniques, including light extinction and laser induce fluorescence and incandescence measurements, are combined to characterize large-molecule soot precursors and soot in a slightly sooting flame of benzene at atmospheric pressure. Light absorption coupled to in-situ light scattering measurements and ex-situ Atomic Force Microscopy also allowed the evaluation of particle sizes. In the benzene flame high molecular mass structures with typical sizes of 3-4nm are formed in the main oxidation region of the flame. The radical-rich flame environment in which these compounds are formed promotes their dehydrogenation increasing the level of their aromaticity. As a result, nanoparticles with typical sizes of about 5nm, absorbing and fluorescing in the visible are formed. These compounds reach a maximum concentration just before the appearance of incandescent soot particles
PROPERTIES OF CARBONACEOUS NANOPARTICLES IN FLAT PREMIXED C2H4/AIR FLAMES FROM STOCHIOMETRIC C/O RATIO TO SOOT APPEARANCE LIMIT
No full textPROPERTIES OF CARBONACEOUS NANOPARTICLES IN FLAT PREMIXED C2H4/AIR FLAMES FROM STOCHIOMETRIC C/O RATIO TO SOOT APPEARANCE LIMIT
No full textTwo classes of aereosols detected in rich methane/oxygen premixed flames above and below the soot threshold
No full textSpectroscopical characterization of carbon-containing aerosols formed in rich premixed flames
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