The shrinkage of bulk polymers by radiation damage in an SEM

Reimer, Ludwig; Schmidt, Annika

doi:10.1002/sca.4950070104

Cited by 15 publications

(6 citation statements)

References 4 publications

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“…However, physical aging and cross-linking in polymeric fibers subjected to the SEM electron beam do not permit its use. 31 Instead, the tension tests were performed under an optical microscope at 500ϫ magnification by recording digital images with 1280 ϫ 1024 pixel resolution. The nanofiber diameter was prohibitively small ͑300-600 nm͒ to view the fiber and measure its elongation directly by using optics.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Furthermore, compared to the variable loading rate that can be accomplished by the approach presented in this article, the use of an SEM allows only for quasistatic tension tests as a result of its rastering action. In our work, the vulnerability of electrospun nanofibers to e-beam radiation, 31 the large fiber ductility, 20 and the strain rate dependent mechanical behavior of the electrospun polymers demanded testing outside an SEM. Thus, the method of subpixel displacement measurements applied here was required to conduct this category of experiments.…”

Section: Introductionmentioning

confidence: 99%

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Novel method for mechanical characterization of polymeric nanofibers

Naraghi

Chasiotis

Kahn

et al. 2007

Review of Scientific Instruments

124

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A novel method to perform nanoscale mechanical characterization of highly deformable nanofibers has been developed. A microelectromechanical system ͑MEMS͒ test platform with an on-chip leaf-spring load cell that was tuned with the aid of a focused ion beam was built for fiber gripping and force measurement and it was actuated with an external piezoelectric transducer. Submicron scale tensile tests were performed in ambient conditions under an optical microscope. Engineering stresses and strains were obtained directly from images of the MEMS platform, by extracting the relative rigid body displacements of the device components by digital image correlation. The accuracy in determining displacements by this optical method was shown to be better than 50 nm. In the application of this method, the mechanical behavior of electrospun polyacrylonitrite nanofibers with diameters ranging from 300 to 600 nm was investigated. The stress-strain curves demonstrated an apparent elastic-perfectly plastic behavior with elastic modulus of 7.6± 1.5 GPa and large irreversible strains that exceeded 220%. The large fiber stretch ratios were the result of a cascade of periodic necks that formed during cold drawing of the nanofibers.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Novel method for mechanical characterization of polymeric nanofibers

Naraghi

Chasiotis

Kahn

et al. 2007

Review of Scientific Instruments

124

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“…Since at high magnification large electron doses are necessary to generate a sufficient S/N ratio, beam damage is of great concern. Thin continuous coatings of 1-2 nm thickness stabilized the surface features against such damage because the metal films provided a sufficient mechanical support (Isaacson, 1977) and prevented volume loss conventionally observed on electron beam radiated uncoated organic particles (Kahler & Lloyd, 1952;Peters & Green, 1983;Reimer & Schmidt, 1985). The thin films prevented excessive electron-specimen interactions and allowed microscopy to be performed directly on the coated bulk organic specimens without the need to prepare a replica from the surface Peters, 1985b).…”

Section: Discussionmentioning

confidence: 99%

“…Highest topographic resolution is established with such a film thickness as is needed to generate sufficient but not excessive contrast. However, metal film application is additionally governed by some practical considerations concerning beam damage during microscopy (Isaacson, 1977;Reimer & Schmidt, 1985). Here, the rationale for thin continuous metal film application is experimentally determined for TEM and SEM.…”

Section: Introductionmentioning

confidence: 99%

Rationale for the application of thin, continuous metal films in high magnification electron microscopy

Peters

1986

Journal of Microscopy

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Various metal films of different thicknesses were deposited on to a particle test specimen and their effects on topographic contrast generation and specimen preservation were determined. Tobacco mosaic virus adsorbed on to thin carbon supports or silicon chips was imaged in TEM or high resolution SE-I SEM at a magnification of 350,OOOX. Tantalum films of 1-2 nm (average mass) thickness produced best contrasts and prevented volume loss of the particles from electron beam damage. Excessively thick films of 5-10 nm thickness blanketed fine structures and caused severe volume losses. Discontinuous 2 nm thick films of gold or platinum decorated the surfaces, caused a loss in topographic contrasts and induced very high volume losses. Thin continuous metal films were necessary to generate high topographic contrast and to prevent volume loss from beam damage by providing sufficient mechanical stability for small topographic features and increased thermal conductivity of the specimen surface.

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“…However, we are not aware of detailed comparisons of LTA and SOA with regards to radiation dose efficiency as well as reconstruction quality. Low radiation dose is critical for X-ray imaging of soft materials, since they are vulnerable to beam-induced damage and distortion [14]. Moreover, other factors may also come into play when one does either SOA or LTA in practice.…”

Section: Introductionmentioning

confidence: 99%

X-ray tomography of extended objects: a comparison of data acquisition approaches

Vescovi

Fezzaa

et al. 2018

J. Opt. Soc. Am. A

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The penetration power of x-rays allows one to image large objects while their short wavelength allows for high spatial resolution. As a result, with synchrotron sources one has the potential to obtain tomographic images of centimeter-sized specimens with sub-micrometer pixel sizes. However, limitations on beam and detector size make it difficult to acquire such data of this sort in a single take, necessitating strategies for combining data from multiple regions. One strategy is to acquire a tiled set of local tomograms by rotating the specimen around each of the local tomogram center positions. Another strategy, sinogram oriented acquisition, involves the collection of projections at multiple offset positions from the rotation axis followed by data merging and reconstruction. We have carried out a simulation study to compare these two approaches in terms of radiation dose applied to the specimen, and reconstructed image quality. Local tomography acquisition involves an easier data alignment problem, and immediate viewing of subregions before the entire dataset has been acquired. Sinogram oriented acquisition involves a more difficult data assembly and alignment procedure, and it is more sensitive to accumulative registration error. However, sinogram oriented acquisition is more dose-efficient, it involves fewer translation motions of the object, and it avoids certain artifacts of local tomography.

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The shrinkage of bulk polymers by radiation damage in an SEM

Cited by 15 publications

References 4 publications

Novel method for mechanical characterization of polymeric nanofibers

Novel method for mechanical characterization of polymeric nanofibers

Rationale for the application of thin, continuous metal films in high magnification electron microscopy

X-ray tomography of extended objects: a comparison of data acquisition approaches

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