Soot nanostructure evolution in premixed flames by High Resolution Electron Transmission Microscopy (HRTEM)

Apicella, B.; Pré, Pascaline; Alfè, Michela; Ciajolo, A.; Gargiulo, Valentina; Russo, Carmela; Tregrossi, A.; Deldique, D.; Rouzaud, Jean-Noël

doi:10.1016/j.proci.2014.06.121

Cited by 129 publications

(99 citation statements)

References 30 publications

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“…[47][48][49]51,52,[54][55][56] The difference in our results may be attributed to the choice of r value assumed in eqn (1), our different approaches to fitting the Urbach region, and the possibility that soot may have a different morphology in different flame systems. 78 The current results correspond well with experimental and computational results from our lab and the Kraft group at Cambridge. Their publication also correlates the measured fringe lengths to the number of aromatic rings, finding the most probable structure containing a 4 by 4 ring structure, which is similar to the size of circumpyrene.…”

Section: Correlation To Molecular Sizesupporting

confidence: 87%

Extinction measurements for optical band gap determination of soot in a series of nitrogen-diluted ethylene/air non-premixed flames

Adkins

Miller

2015

Phys. Chem. Chem. Phys.

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Visible light extinction was measured in a series of nitrogen-diluted, ethylene/air, non-premixed flames and this data was used to determine the optical band gap, OBG, as a function of flame position. Collimated light from a supercontinuum source is telescopically expanded and refocused to match the f- number of a dispersing monochromator. The dispersed light is split into a power metering channel and a channel that is periscoped and focused into the flame. The transmitted light is then recollimated and focussed onto a silicon photodiode detector. After tomographic reconstruction of the radial extinction field, the OBG was derived from the near-edge absorption feature using Tauc/Davis-Mott analysis. A slight evolution in OBG was observed throughout all flame systems with a consistent range of OBG observed between approximately 1.85 eV and 2.35 eV. Averaging over all positions the mean OBG was approximately 2.09 eV for all flame systems. Comparing these results to previously published computational results relating calculated HOMO-LUMO gaps for a variety of D2h PAH molecules to the number of aromatic rings in the structure, showed that the observed optical band gap is consistent with a PAH of about 14 rings or a conjugation length of 0.97 nm. This work provides experimental support to the model of soot formation where the transition from chemical to physical growth starts at a modest molecular size; about the size of circumpyrene.

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Section: Correlation To Molecular Sizesupporting

confidence: 87%

Extinction measurements for optical band gap determination of soot in a series of nitrogen-diluted ethylene/air non-premixed flames

Adkins

Miller

2015

Phys. Chem. Chem. Phys.

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“…At longer reaction time, equivalently at a higher HAB, the soot molecular precursors react to form condensed-phase nascent soot particles. In controlled, low-sooting laboratory flames, nascent soot particles as small as 2 nm can be detected (Betrancourt et al, 2017). The dynamic equilibrium between the heterogeneous reactions at the particle surface (surface growth and oxidation) in concert with coalescence and coagulation phenomena determine whether the newly formed particles increase their size or are re-oxidized into gas-phase products.…”

Section: Introductionmentioning

confidence: 99%

Influence of the dry aerosol particle size distribution and morphology on the cloud condensation nuclei activation. An experimental and theoretical investigation

Faccinetto

Grimonprez

et al. 2020

Atmos. Chem. Phys.

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Combustion and other high-temperature processes frequently result in the emission of aerosols in the form of polydisperse fractal-like aggregates made of condensedphase nanoparticles (soot for instance). If certain conditions are met, the emitted aerosol particles are known to evolve into important cloud condensation nuclei (CCN) in the atmosphere. In this work, the hygroscopic parameter κ of complex morphology aggregates is calculated from the supersaturation-dependent activated fraction F a = F a (SS) in the frame of κ-Köhler theory. The particle size distribution is approximated with the morphology-corrected volume equivalent diameter calculated from the electrical mobility diameter by taking into account the diameter of the primary particle and the fractal dimension of the aggregate experimentally obtained from transmission electron microscopy measurements. Activation experiments are performed in water supersaturation conditions using a commercial CCN-100 condensation nuclei counter. The model is tested in closeto-ideal conditions of size-selected, isolated spherical particles (ammonium sulfate nanoparticles dispersed in nitrogen), then with complex polydisperse fractal-like aggregates (soot particles activated by exposure to ozone with κ as low as 5 × 10 −5 ) that represent realistic anthropogenic emissions in the atmosphere.

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“…They further argue that partially closed carbon clusters may collide and stick together while open shells continue to grow forming layers around the adducts; an explanation that is consistent with experimental high-resolution transmission electron microscopy (HRTEM) images of soot collected from flames which show multiple centres surrounded by concentric circles (see, e.g., ref. [5][6][7][8][9]). Quantitative measurements of these sheet-like PAHs otherwise referred to as lattice fringes have been made including measurements such as the fringe length, interlayer spacing and, more rarely, radius of curvature [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…[5][6][7][8][9]). Quantitative measurements of these sheet-like PAHs otherwise referred to as lattice fringes have been made including measurements such as the fringe length, interlayer spacing and, more rarely, radius of curvature [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…The purpose of this paper is to extend the PAH-PP/KMC-ARS model such that we can not only track PAHs but also allow the inclusion of 5member rings and to track the associated change in curvature using the Gauss-Bonnet theorem. Computed fringe length distributions are also compared with experimental measurements [6]. As fringe length is thought to be related to PAH size, these comparisons allow us to investigate the minimum PAH sizes required for inception and condensation which may be different.…”

Section: Introductionmentioning

confidence: 99%

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Modelling PAH curvature in laminar premixed flames using a detailed population balance model

Yapp

Wells

Akroyd

et al. 2017

Combustion and Flame

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A detailed population balance model, which includes the kinetic Monte Carloaromatic site (KMC-ARS) model for detailed polycyclic aromatic hydrocarbon (PAH) growth, is used to compute the Gauss curvature of PAHs in laminar premixed ethylene and benzene flames. Previous studies have found that capping of an embedded 5-member ring causes curvature in graphene edges. In this work, a capping process is added to the KMC-ARS model with the rate coefficient of the capping reaction taken from the work of You et al. [Proc. Combust. Inst., 33:685-692, 2011]. We demonstrate that the Gauss-Bonnet theorem can be used to derive a correlation between the number of 5-and 6-member rings in a PAH and its Gauss curvature (or radius of curvature), independent of where the 5-member ring is embedded within the PAH structure. Numerical simulation yields satisfactory results when compared to the experimentally determined Gauss curvature reported in the literature. Computed and experimental fringe length distributions are also compared and the results suggest that PAHs smaller than the size required for inception are able to condense onto particles.

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Soot nanostructure evolution in premixed flames by High Resolution Electron Transmission Microscopy (HRTEM)

Cited by 129 publications

References 30 publications

Extinction measurements for optical band gap determination of soot in a series of nitrogen-diluted ethylene/air non-premixed flames

Extinction measurements for optical band gap determination of soot in a series of nitrogen-diluted ethylene/air non-premixed flames

Influence of the dry aerosol particle size distribution and morphology on the cloud condensation nuclei activation. An experimental and theoretical investigation

Modelling PAH curvature in laminar premixed flames using a detailed population balance model

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