Comparison of STEM EELS Spectrum Imaging vs EFTEM Spectrum Imaging

Hunt, John; Kothleitner, Gerald; Harmon, R.

doi:10.1017/s1431927600016408

Cited by 15 publications

(3 citation statements)

References 5 publications

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“…In both spectrum imaging and image spectroscopy, the final data set is a three‐dimensional cube with two positional axes and one energy axis. Hunt et al . (1999) discuss the similarities and differences between image spectroscopy and spectrum imaging.…”

Section: Future Directionsmentioning

confidence: 99%

Electron energy‐loss near‐edge structure – a tool for the investigation of electronic structure on the nanometre scale

Keast

Scott

Brydson

et al. 2001

Journal of Microscopy

179

116

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SummaryElectron energy-loss near-edge structure (ELNES) is a technique that can be used to measure the electronic structure (i.e. bonding) in materials with subnanometre spatial resolution. This review covers the theoretical principles behind the technique, the experimental procedures necessary to acquire good ELNES spectra, including potential artefacts, and gives examples relevant to materials science.

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Section: Future Directionsmentioning

confidence: 99%

Electron energy‐loss near‐edge structure – a tool for the investigation of electronic structure on the nanometre scale

Keast

Scott

Brydson

et al. 2001

Journal of Microscopy

179

116

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“…These studies also reveal that the propagation of Ca 2+ signals has a strong spatial component, driving home the need for spatially resolved measurements in future studies. This in turn point to a future goal for analytical microscopy-the continued development of high-resolution imaging approaches, such as EELS spectrum imaging [8][9][10].…”

mentioning

confidence: 99%

Correlated Measurements Of Free And Total Intracellular Calcium

et al. 2003

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Transient changes in the intracellular distribution of calcium ions act as a trigger for a large number of important physiological functions [1,2]. The nature of intracellular Ca changes is complex, however, because Ca is dynamically distributed between several compartments, the most important being the cytosol, mitochondria and the endoplasmic reticulum (ER). Within each compartment, Ca is further partitioned between a large pool bound to buffers (mainly proteins) and a much smaller pool of "free Ca 2+ ." Although small, concentration changes in the latter pools, especially cytosolic free Ca 2+ ([Ca 2+ ] i ), are especially critical for signal transduction. To obtain a general picture of the interactions and spatio-temporal concentration fluctuations that underlie Ca 2+ signaling, correlated measurements of both free and bound Ca pools are highly advantageous [3]. Optical imaging of fluorescent indicators in living cells is the method of choice for measuring [Ca 2+ ] i , while analytical electron microscopy-either electron probe x-ray microanalysis (EPMA) or electron energy loss spectroscopy (EELS)-is the well established approach for determining total Ca (essentially equivalent to bound Ca) within specific subcellular compartments. When these techniques are used in tandem, the combined information provides unique insights into the regulation of Ca 2+ signaling.To illustrate the kinds of information available with this approach, we present here results from recent work aimed at elucidating the role of mitochondrial and ER Ca 2+ transport in the modulation of Ca 2+ signaling in neurons.Our first example explores the role of mitochondrial Ca 2+ uptake in blunting the impact of depolarization-induced Ca 2+ entry on the signaling Ca 2+ pool, i.e., on [Ca 2+ ] i [4,5]. Optical measurements (fura-2) show that sympathetic neurons respond to depolarization with a rise in [Ca 2+ ] i that has several prominent phases (Fig. 1, upper panel). Following a sharp initial rise, [Ca 2+ ] i is clamped at a steady elevated concentration (~750 nM for a depolarization to ~0 mV) for the duration of the stimuli (<2 min), even though Ca 2+ entry continues; upon repolarization (which closes membrane channels and stops Ca 2+ influx), [Ca 2+ ] i recovers only slowly, exhibiting a plateau phase ([Ca 2+ ] ĩ 400 nM) of several minutes duration (arrow). The explanation for this complex behavior is revealed by parallel EMPA measurements of mitochondrial total calcium ([Ca] MT ) ( Fig. 1, lower panel), which show that: 1) continuous Ca 2+ uptake by mitochondria during sustained stimulation targets entering Ca 2+ directly into mitochondria, thereby accounting for the blunted rise and clamped phase of [Ca 2+ ] i ; and 2) subsequent release of the accumulated mitochondrial Ca load, at a rate determined by the responsible transporters and of a length determined by the size of the load, underlies the delayed [Ca 2+ ] i recovery.During the recovery phase, ER Ca 2+ transport also comes into play [6]. EPMA data on total ER Ca concentrations ([Ca] ER ),...

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“…Use of an optimized CCD detector in the EFTEM now enables accurate quantitation ih addition to high analytical sensitivity, albeit not at the single atom level. 6,7 Our aim here is to review the current capabilities of both the scanned beam and fixed-beam EELS techniques for biological applications.…”

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confidence: 99%

Analysis of Biological Structures by Electron Energy Loss Spectroscopy and Imaging

Leapman¹,

Andrews

2001

Microsc Microanal

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As techniques for electron energy-loss spectroscopy (EELS) reach a higher degree of optimization, detection limits for analyzing biological structures are approaching those predicted by theory. in favorable specimens, single atom detection is predicted for elemental maps acquired by means of the scanning transmission electron microscope (STEM) equipped with a field emission source, paralleldetection EELS and a spectrum-imaging system. to obtain such results, the electron detector should have a detective quantum efficiency close to unity and a well behaved point-spread function; such design features are now available with a cooled charge-couple device (CCD) array. The energy-filtering transmission electron microscope (EFTEM) provides a complementary approach to mapping elements occurring at higher concentrations but distributed over larger regions of the specimen. Use of an optimized CCD detector in the EFTEM now enables accurate quantitation in addition to high analytical sensitivity, albeit not at the single atom level.

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Comparison of STEM EELS Spectrum Imaging vs EFTEM Spectrum Imaging

Cited by 15 publications

References 5 publications

Electron energy‐loss near‐edge structure – a tool for the investigation of electronic structure on the nanometre scale

Electron energy‐loss near‐edge structure – a tool for the investigation of electronic structure on the nanometre scale

Correlated Measurements Of Free And Total Intracellular Calcium

Analysis of Biological Structures by Electron Energy Loss Spectroscopy and Imaging

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