Carbonaceous contaminants on support films for transmission electron microscopy

Harris, Peter

doi:10.1016/s0008-6223(00)00195-0

Cited by 19 publications

(8 citation statements)

References 9 publications

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“…A few titanium (Ti) and zinc (Zn) oxide particles, as well as few pure C particles were encountered on the blank samples. They look similar to some carbonaceous particles being described as contaminants on TEM grids (Harris et al, 2001). However, these particles are different in both size and morphology compared to the carbonaceous particles observed in the impaction spot of the samples.…”

Section: Electron Microscopysupporting

confidence: 52%

Sub-micrometer refractory carbonaceous particles in the polar stratosphere

et al. 2017

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Abstract. Eleven particle samples collected in the polar stratosphere during SOLVE (SAGE III Ozone loss and validation experiment) from January until March 2000 were characterized in detail by high-resolution transmission and scanning electron microscopy (TEM/SEM) combined with energy-dispersive X-ray microanalysis. A total of 4202 particles (TEM = 3872; SEM = 330) were analyzed from these samples, which were collected mostly inside the polar vortex in the altitude range between 17.3 and 19.9 km. Particles that were volatile in the microscope beams contained ammonium sulfates and hydrogen sulfates and dominated the samples. Some particles with diameters ranging from 20 to 830 nm were refractory in the electron beams. Carbonaceous particles containing additional elements to C and O comprised from 72 to 100 % of the refractory particles. The rest were internal mixtures of these materials with sulfates. The median number mixing ratio of the refractory particles, expressed in units of particles per milligram of air, was 1.1 (mg air) −1 and varied between 0.65 and 2.3 (mg air) −1 .Most of the refractory carbonaceous particles are completely amorphous, a few of the particles are partly ordered with a graphene sheet separation distance of 0.37 ± 0.06 nm (mean value ± standard deviation). Carbon and oxygen are the only detected major elements with an atomic O/C ratio of 0.11 ± 0.07. Minor elements observed include Si, S, Fe, Cr and Ni with the following atomic ratios relative to C: Si/C: 0.010 ± 0.011; S/C: 0.0007 ± 0.0015; Fe/C: 0.0052 ± 0.0074; Cr/C: 0.0012 ± 0.0017; Ni/C: 0.0006 ± 0.0011 (all mean values ± standard deviation).High-resolution element distribution images reveal that the minor elements are distributed within the carbonaceous matrix; i.e., heterogeneous inclusions are not observed. No difference in size, nanostructure and elemental composition was found between particles collected inside and outside the polar vortex.Based on chemistry and nanostructure, aircraft exhaust, volcanic emissions and biomass burning can certainly be excluded as sources. The same is true for the less probable but globally important sources: wood burning, coal burning, diesel engines and ship emissions.Recondensed organic matter and extraterrestrial particles, potentially originating from ablation and fragmentation, remain as possible sources of the refractory carbonaceous particles studied. However, additional work is required in order to identify the sources unequivocally.

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Section: Electron Microscopysupporting

confidence: 52%

Sub-micrometer refractory carbonaceous particles in the polar stratosphere

et al. 2017

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“…Figure (b) shows the HAADF image retaken after the EELS spectrum imaging, in which an increase in the thickness of the corona is clearly observed, indicating a buildup of a carbon-rich substance as a result of electron bombardment. It is known that electron beam irradiation especially at high electron dose that is normally required for EELS spectrum imaging can induce specimen contamination by formation of a carbonaceous layer on the sample surface. , However, these carbon-rich deposits formed by the specimen contamination do not contain a detectable O constituent, so it is clear that the corona does not come from a buildup of carbon contamination from electron beam damage. This can be easily identified by comparing the O map in Figure (e) with the STEM images in Figure (a, b), which show the HAADF images taken before and after the spectrum image 4(c) was recorded.…”

Section: Resultsmentioning

confidence: 99%

High Resolution STEM-EELS Study of Silver Nanoparticles Exposed to Light and Humic Substances

Römer

Wang

Merrifield

et al. 2016

Environ. Sci. Technol.

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Nanoparticles (NPs) are defined as particles with at least one dimension between 1 and 100 nm or with properties that differ from their bulk material, which possess unique properties. The extensive use of NPs means that discharge to the environment is likely increasing, but fate, behavior, and effects under environmentally relevant conditions are insufficiently studied. This paper focuses on the transformations of silver nanoparticles (AgNPs) under simulated but realistic environmental conditions. High resolution aberration-corrected scanning transmission electron microscopy (HAADF STEM) coupled with electron energy loss spectroscopy (EELS) and UV-vis were used within a multimethod approach to study morphology, surface chemistry transformations, and corona formation. Although loss, most likely by dissolution, was observed, there was no direct evidence of oxidation from the STEM-EELS. However, in the presence of fulvic acid (FA), a 1.3 nm oxygen-containing corona was observed around the AgNPs in water; modeled data based on the HAADF signal at near atomic resolution suggest this was an FA corona was formed and was not silver oxide, which was coherent (i.e., fully coated in FA), where observed. The corona further colloidally stabilized the NPs for periods of weeks to months, dependent on the solution conditions.

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“…50 nm, a small hollow core was surrounded by many layers of graphitic carbon. Subsequent work has shown that nanoparticles of this kind are sometimes found in the carbon support lms used for TEM (Harris 1997a(Harris , 2001. Therefore, the particles observed by Smith and Buseck may not have been part of the meteoritic carbon, but a contaminant.…”

Section: Introductionmentioning

confidence: 99%

High-resolution transmission electron microscopy of carbon and nanocrystals in the Allende meteorite

Harris

Vis

2003

Proc. R. Soc. Lond. A

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Transmission electron microscopy has been used to examine carbon extracted from the Allende meteorite. The structure of the carbon is rather disordered, consisting of curved and faceted graphitic sheets which often enclose voids of the order of 2{10 nm in size. Completely closed fullerene particles are quite commonly observed. This carbon is a strong candidate to be a carrier of planetary gases. Carbon-coated crystallites, which appear to be iron sulphide, are also found in the carbon.

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Carbonaceous contaminants on support films for transmission electron microscopy

Cited by 19 publications

References 9 publications

Sub-micrometer refractory carbonaceous particles in the polar stratosphere

Sub-micrometer refractory carbonaceous particles in the polar stratosphere

High Resolution STEM-EELS Study of Silver Nanoparticles Exposed to Light and Humic Substances

High-resolution transmission electron microscopy of carbon and nanocrystals in the Allende meteorite

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