Challenges in Characterizing Small Particles Exploring Particles from the Nano- to Microscale: A Workshop Summary (2012) / Chapter Skim
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3 Analysis and Imaging of Small Particles
3 Analysis and Imaging of Small Particles
Pages 21-36
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From page 21... ...
They also are examining INDIVIDUAL AEROSOL PARTICLES different aspects of particle shape and dynamic shape factor, Alla Zelenyuk of the Pacific Northwest National Labo- that is, whether a particle is spherical or symmetric, and ratory (PNNL) reiterated the important point that aerosols particle morphology in terms of what is on the outside of the are everywhere, with impacts on the climate and health and particle.
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From page 22... ...
R02144 Figure 3-1 uneditable raster bitmap FIGURE 3-2 SPLAT II, an ultrasensitive high-precision instrument for multidimensional single particle characterization. SOURCE: Zelenyuk, 2010; modified from Zelenyuk et al., 2009.
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From page 23... ...
uneditable raster bitmap One series of measurements, for example, showed that particle chemistry MATERIALS DESIGN AND SYNTHESIS changed as the aircraft travelled through a cloud, implying In his presentation, Ralph Nuzzo from the University that the chemistry in a cloud is heterogeneous and changing with location and over time. Another set of experiments of Illinois in Urbana-Champaign discussed his work on found that a thin layer of organics can reduce particle evapo- nanoscale characterization from the perspective of underration by 96 percent over 24 hours.
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From page 24... ...
with permission from Sanchez et al., 2009a. R02144 nucleation and growth and have provided input for modeling Figure 3-4 a detailed modeling study, combined with nano-area work, studies that have advanced our theoretical understanding of coherent electron diffraction data of gold nanoparticles, uneditable raster bitmap the vertices of gold clusters are deformed more these important processes.
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SOURCE: Zuo et al., 2003. R02144 Figure 3-5 uneditable raster bitmap FIGURE 3-6 Coherent diffractive imaging was used to refine a low-resolution image of a cadmium selenide quantum dot (left)
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From page 26... ...
and nanotechnology enables you to combine different property sets into specific materials." As examples, Silverman Probing Complex Materials said that nanoparticles added to a polymer can improve its rheological properties in the molten state and its mechanical Although it is interesting scientifically to examine single properties once the material has cooled. Nanomaterials can particles, polymer chemists are more interested in materials add barrier properties to a film while enabling it to remain with high loadings of the nanoscale filler, and analysis at transparent.
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From page 27... ...
Studies on particle shape, size, and size distribution are critical deterpermeability conducted in the late 1960s showed that rela- minants not only for creating useful materials but also for tive permeability falls substantially as the aspect ratio of the understanding how they will behave from an environment, nanorod increases (Nielsen, 1967)
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From page 28... ...
That idea was proven wrong when it was observed that the quantities of material that need to be analyzed fall that there can be sudden bursts of particle formation when the in the picogram range. Ideally, Smith will collect about atmospheric boundary layer (part of troposphere closest to 15 picograms of 5-nanometer particles, but at best, he will the Earth's surface)
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From page 29... ...
Datye noted that recent work with environment and climate, and that, explained Smith, requires gold nanoparticles on a titanium dioxide support showed more and better atmospheric measurements. unexpected activity in catalyzing oxidation of carbon mon oxide.
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Its two arrows point to reflec tions of the hexagonal BN that correspond to recorded spacings of 1.26 and 1.09 Å. The image was recorded at 60 kV primary voltage, and uneditable raster bitmap the probe size was about 1.2 Å.
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From page 31... ...
As a final example of measure size changes within a useful timeframe. Dielectrothe type of structural detail that modern microscopy can pro phoresis is proving useful for characterizing larger particles, vide, Datye described the use of high angular annular dark even in the micron range, in manufacturing settings.
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SOURCE: Qiao, 2010. R02144 Figure 3-10 uneditable raster bitmap FIGURE 3-11 In a microfluidic Y-cell, a laser beam shows no deflection prior to the admission of nanoparticles into the channel (top)
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In particular, One approach to studying cosmic nanoparticles is to the particles in the 100-micron range, which make up most map the isotopic signature of individual grains of a meteof the dust's mass, vaporize completely (Figure 3-12)
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C Fe Fe,Ni Disordered carbon vacuum 100 nm 1 nm FIGURE 3-13 Z-contrast imaging and energy dispersive spec FIGURE 3-14 Dark-field scanning transmission electron microtroscopy reveal subgrain structure and elemental composition of a R02144 silicon carbide cosmic nanoparticle. graph of cosmic particles from the Murchison meteorite.
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From page 35... ...
Nuzzo replied that entire Discussion industries have been built on conducting catalysis under When asked by Barbara Finlayson-Pitts about how the reducing conditions, including the petrochemical industry, noble gas neon manages to remain in a dust fragment for but he agreed that interesting oxidative reaction conditions billions of years, Stroud said that the noble gas atoms are require the same amount of attention. Doing so is proving only seen when more than one layer of carbon is present.
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