Energy Filtering and Spectrum Imaging of Polymers

2000 ◽  
Vol 6 (S2) ◽  
pp. 1116-1117
Author(s):  
A. Aitouchen ◽  
J. Taylor ◽  
P. Crozier ◽  
M. Libera
Keyword(s):  
Imaging Techniques ◽  
Polymeric Materials ◽  
Chemical Imaging ◽  
Polymer Particle ◽  
Initial Image ◽  
Image Region ◽  
Energy Filtering ◽  
Spectrum Imaging ◽  
Field Imaging ◽  
Tem Grid

Chemical imaging of polymeric materials is attractive, because of the inherently poor contrast typically afforded by multiphase amorphous polymers in bright-field imaging techniques. Spectrum imaging and energy-filtering approaches are being increasing applied to polymeric materials (1,2, 3).One recent example from the Stevens group using a Philips CM20 FEG TEM/STEM interfaced to an EmiSpec Vision data acquisition/control system and a Gatan 666 PEELS spectrometer is presented in figure 1. The specimen is a PVP sphere on a holey-carbon TEM grid. The specimen was cooled to approximately -125 °C in a single-tilt cryo stage. Drift correction was implemented by collecting HAADF STEM images from the sub-image region indicated by the dashed white box at periodic intervals. Based on an autocorrelation with the initial image, electronic shifts where imposed to correct for drift. A 3-D spectrum dataset was generated from the 70 x 70 pixel box around the polymer particle at an interpixel spacing of 5 nm and a pixel dwell time of 1.5 sec.

Image formation analysis of thick biological specimens using three-dimensional power-spectra of through focus series

1994 ◽  
Vol 52 ◽  
pp. 124-125
Author(s):  
Karen F. Han
Keyword(s):  
Inelastic Scattering ◽  
Imaging Techniques ◽  
Mass Density ◽  
Relative Proportion ◽  
Three Dimensional ◽  
Power Spectra ◽  
Image Formation ◽  
Energy Filtering ◽  
Ewald Sphere ◽  
Nonlinear Imaging

The primary focus in our laboratory is the study of higher order chromatin structure using three dimensional electron microscope tomography. Three dimensional tomography involves the deconstruction of an object by combining multiple projection views of the object at different tilt angles, image intensities are not always accurate representations of the projected object mass density, due to the effects of electron-specimen interactions and microscope lens aberrations. Therefore, an understanding of the mechanism of image formation is important for interpreting the images. The image formation for thick biological specimens has been analyzed by using both energy filtering and Ewald sphere constructions. Surprisingly, there is a significant amount of coherent transfer for our thick specimens. The relative amount of coherent transfer is correlated with the relative proportion of elastically scattered electrons using electron energy loss spectoscopy and imaging techniques.Electron-specimen interactions include single and multiple, elastic and inelastic scattering. Multiple and inelastic scattering events give rise to nonlinear imaging effects which complicates the interpretation of collected images.

scholarly journals Development of a New Acquisition Scheme for Energy-Filtering Transmission Electron Microscopy Spectrum-Imaging toward Quantification

2011 ◽  
Vol 17 (S2) ◽  
pp. 790-791
Author(s):  
M Watanabe ◽  
F Allen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Filtering ◽  
Transmission Electron ◽  
Acquisition Scheme ◽  
Spectrum Imaging

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Raman Chemical Imaging of Explosive-Contaminated Fingerprints

2009 ◽  
Vol 63 (11) ◽  
pp. 1197-1203 ◽  
Author(s):  
E. D. Emmons ◽  
A. Tripathi ◽  
J. A. Guicheteau ◽  
S. D. Christesen ◽  
A. W. Fountain
Keyword(s):  
Cross Correlation ◽  
Chemical Imaging ◽  
Correlation Technique ◽  
Bright Field ◽  
Characteristic Region ◽  
Biometric Analysis ◽  
Imaging Results ◽  
Raman Chemical Imaging ◽  
Cross Correlation Technique ◽  
Field Imaging

Raman chemical imaging (RCI) has been used to detect and identify explosives in contaminated fingerprints. Bright-field imaging is used to identify regions of interest within a fingerprint, which can then be examined to determine their chemical composition using RCI and fluorescence imaging. Results are presented where explosives in contaminated fingerprints are identified and their spatial distributions are obtained. Identification of explosives is obtained using Pearson's cosine cross-correlation technique using the characteristic region (500–1850 cm−1) of the spectrum. This study shows the ability to identify explosives nondestructively so that the fingerprint remains intact for further biometric analysis. Prospects for forensic examination of contaminated fingerprints are discussed.

scholarly journals Spectrum Imaging Techniques Applied to Forensics Investigations

2005 ◽  
Vol 11 (S02) ◽  
Author(s):  
L N Brewer ◽  
P G Kotula ◽  
J A Ohlhausen ◽  
J R Michael
Keyword(s):  
Imaging Techniques ◽  
Spectrum Imaging

scholarly journals An ecophysiological explanation for manganese enrichment in rock varnish

2021 ◽  
Vol 118 (25) ◽  
pp. e2025188118
Author(s):  
Usha F. Lingappa ◽  
Chris M. Yeager ◽  
Ajay Sharma ◽  
Nina L. Lanza ◽  
Demosthenes P. Morales ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Imaging Techniques ◽  
Manganese Content ◽  
Chemical Imaging ◽  
Arid Environments ◽  
Metagenomic Dna ◽  
Paramagnetic Resonance ◽  
Desert Varnish ◽  
Specific Uptake ◽  
Petrographic Thin Section

Desert varnish is a dark rock coating that forms in arid environments worldwide. It is highly and selectively enriched in manganese, the mechanism for which has been a long-standing geological mystery. We collected varnish samples from diverse sites across the western United States, examined them in petrographic thin section using microscale chemical imaging techniques, and investigated the associated microbial communities using 16S amplicon and shotgun metagenomic DNA sequencing. Our analyses described a material governed by sunlight, water, and manganese redox cycling that hosts an unusually aerobic microbial ecosystem characterized by a remarkable abundance of photosynthetic Cyanobacteria in the genus Chroococcidiopsis as the major autotrophic constituent. We then showed that diverse Cyanobacteria, including the relevant Chroococcidiopsis taxon, accumulate extraordinary amounts of intracellular manganese—over two orders of magnitude higher manganese content than other cells. The speciation of this manganese determined by advanced paramagnetic resonance techniques suggested that the Cyanobacteria use it as a catalytic antioxidant—a valuable adaptation for coping with the substantial oxidative stress present in this environment. Taken together, these results indicated that the manganese enrichment in varnish is related to its specific uptake and use by likely founding members of varnish microbial communities.

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