Fractal parameters of individual soot particles determined using electron tomography: Implications for optical properties

Adachi, Kouji; Chung, S. H.; Friedrich, Heiner; Buseck, Peter R.

doi:10.1029/2006jd008296

Cited by 143 publications

(183 citation statements)

References 60 publications

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“…The morphology of soot agglomerates is very well-known (25)(26)(27)(28)(29). Submicrometer particles consist of chains of primary particles with sizes of ∼30 nm (26,30).…”

Section: Emission Samples 311 Tem Observationsmentioning

confidence: 99%

On Source Identification and Alteration of Single Diesel and Wood Smoke Soot Particles in the Atmosphere; An X-Ray Microspectroscopy Study

Vernooij

Mohr

Tzvetkov

et al. 2009

Environ. Sci. Technol.

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Diesel and wood combustion are major sources of carbonaceous particles in the atmosphere. It is very hard to distinguish between the two sources by looking at soot particle morphology, but clear differences in the chemical structure of single particles are revealed by C(1s) NEXAFS (near edge X-ray absorption fine structure) microspectroscopy. Soot from diesel combustion has a dominant spectral signature at ∼285 eV from aromatic π-bonds, whereas soot from wood combustion has the strongest signature at ∼287 eV from phenolic carbon bonds. To investigate if it is possible to use these signatures for source apportionment purposes, we collected atmospheric samples with either diesel or wood combustion as a dominant particle source. No spectra obtained from the atmospheric particles completely matched the emission spectra. Especially particles from the wood dominated location underwent large modifications; the phenolic spectral signature at ∼287 eV is greatly suppressed and surpassed by the peak attributed to the aromatic carbon groups at ∼285 eV. Comparison with spectra from diesel soot samples experimentally aged with ozone show that very fast modification of the carbon structure of soot particles occurs as soon as they enter the atmosphere. Source attribution of single soot particles with microspectroscopy is thus hardly possible, but NEXAFS remains a powerful tool to study aging effects.

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“…The morphology of soot agglomerates is very well-known (25)(26)(27)(28)(29). Submicrometer particles consist of chains of primary particles with sizes of ∼30 nm (26,30).…”

Section: Emission Samples 311 Tem Observationsmentioning

confidence: 99%

On Source Identification and Alteration of Single Diesel and Wood Smoke Soot Particles in the Atmosphere; An X-Ray Microspectroscopy Study

Vernooij

Mohr

Tzvetkov

et al. 2009

Environ. Sci. Technol.

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“…Visual scanning is rapid and can be used to select a relatively small number of particles that appear to be representative and, if appropriate, can then be subjected to detailed studies using electron tomography to determine their 3D shapes (van Poppel et al 2005;Adachi et al 2007). Morphology and mixing state strongly influence the scattering cross-sections of ns-soot.…”

Section: Associated Materials Coating Embeddingmentioning

confidence: 99%

“…For example, ns-soot from East Asia had 139 nanospheres on average (range: 7 to 509) and that from Arizona traffic had 203 (range: 47 to 792; Adachi et al 2007). Samples from Mexico City had 40 § 32 nanospheres in nssoot (Adachi et al 2010).…”

mentioning

confidence: 99%

Ns-Soot: A Material-Based Term for Strongly Light-Absorbing Carbonaceous Particles

Buseck

Adachi

Gelencsér

et al. 2014

Aerosol Science and Technology

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The climate-change and environmental literature, including that on aerosols, is replete with mention of black carbon (BC) and soot. The terms are used interchangeably in much of the literature, although BC and soot commonly have operational and source-based definitions, respectively, and reliable reference samples and aerosol standards do not exist for either one. The uncertainty about their exact chemical nature and properties can be decreased by materials-based measurement techniques and terminology. Here, we discuss ambiguities in common uses of BC and soot and propose the term ns-soot, where "ns" refers to carbon nanospheres, for a characteristic constituent of BC and soot. Based on its composition, morphology, and structure, we define ns-soot as particles that consist of nanospheres, typically with diameters <100 nm, that possess distinct structures of concentrically wrapped, graphene-like layers of carbon and with grape-like (aciniform) morphologies. We additionally propose that, because of their importance for climate modeling and health issues, distinctions are made among bare, coated, and embedded ns-soot particles.

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“…The development of techniques to easily measure aspect ratios for samples would help our analysis of field and laboratory samples because each sample of interest could be measured rather than depending on literature values for representative compounds. Where additional information is needed for complex particles, more time-consuming techniques such as electron tomography and focused ion beam SEM imaging can be used to obtain three-dimensional shape and composition information of particles (van Poppel et al 2005;Adachi et al 2007;Adler et al 2013;Conny 2013).…”

Section: Introductionmentioning

confidence: 99%

Facile Method for Determining the Aspect Ratios of Mineral Dust Aerosol by Electron Microscopy

Veghte

Freedman

2014

Aerosol Science and Technology

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Mineral dust is the second largest atmospheric emission by mass and one of the least understood sources. The shape of the particles depends on their composition and has implications for particle optical properties and reactive surface area. Mineral dust particles are often approximated as spheroids to model their optical properties. In this study, scanning electron microscopy (SEM) is used to measure the aspect ratios of calcite, quartz, NXillite, kaolinite (KGa-1b and KGa-2), and montmorillonite (STx1b and SWy-2). In addition to traditional SEM images of the top of the particles, the SEM substrates are oriented approximately normal to the electron beam in order to image the side of the particles. In this manner, aspect ratios for the top and side orientation of the particles are determined. Calcite particles have an aspect ratio of approximately 1.3 in both orientations, while quartz particles have an aspect ratio of 1.38 in the top orientation and 1.64 in the side orientation. The clay minerals studied all exhibited plate-like structures with aspect ratios of 1.35 to 1.44 for the top orientation and 4.80 to 9.14 for the side orientation. These values are used to estimate the specific surface areas (SSAs) of the minerals, which are compared to BrunauerEmmett-Teller (BET) surface area measurements. Through this study, we present a simple method for determining the aspect ratios of aerosolized samples, rather than relying on literature values of model systems. As a result, this technique should provide a better method for determining the optical properties of mineral dust particles.

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Fractal parameters of individual soot particles determined using electron tomography: Implications for optical properties

Cited by 143 publications

References 60 publications

On Source Identification and Alteration of Single Diesel and Wood Smoke Soot Particles in the Atmosphere; An X-Ray Microspectroscopy Study

On Source Identification and Alteration of Single Diesel and Wood Smoke Soot Particles in the Atmosphere; An X-Ray Microspectroscopy Study

Ns-Soot: A Material-Based Term for Strongly Light-Absorbing Carbonaceous Particles

Facile Method for Determining the Aspect Ratios of Mineral Dust Aerosol by Electron Microscopy

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