Thick specimens in the CEM and STEM. Resolution and image formation

Groves, Timothy R.

doi:10.1016/s0304-3991(75)80005-2

Cited by 54 publications

(17 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…STEM images of thick specimens appear blurry due to spreading of the incident beam caused by multiple elastic scattering [36, 37]. As it was pointed out by Rose and Fertig [34], Groves [36] and Gentsch et al [37], image resolution from a thick section could depend to some extent on STEM detector geometry.…”

Section: Resultsmentioning

confidence: 99%

“…As it was pointed out by Rose and Fertig [34], Groves [36] and Gentsch et al [37], image resolution from a thick section could depend to some extent on STEM detector geometry. Therefore, here we apply Monte Carlo simulation to quantitatively investigate the extent to which image blurring in thick stained biological sections varies with the specific configuration of the STEM detection system.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Monte Carlo electron-trajectory simulations in bright-field and dark-field STEM: Implications for tomography of thick biological sections

et al. 2009

View full text Add to dashboard Cite

A Monte Carlo electron-trajectory calculation has been implemented to assess the optimal detector configuration for scanning transmission electron microscopy (STEM) tomography of thick biological sections. By modeling specimens containing 2 and 3 atomic % osmium in a carbon matrix, it was found that for 1-μm thick samples the bright-field (BF) and annular dark-field (ADF) signals give similar contrast and signal-to-noise ratio provided the ADF inner angle and BF outer angle are chosen optimally. Spatial resolution in STEM imaging of thick sections is compromised by multiple elastic scattering which results in a spread of scattering angles and thus a spread in lateral distances of the electrons leaving the bottom surface. However, the simulations reveal that a large fraction of these multiply scattered electrons are excluded from the BF detector, which results in higher spatial resolution in BF than in high-angle ADF images for objects situated towards the bottom of the sample. The calculations imply that STEM electron tomography of thick sections should be performed using a BF rather than an ADF detector. This advantage was verified by recording simultaneous BF and high-angle ADF-STEM tomographic tilt series from a stained 600-nm thick section of C. elegans. It was found that loss of spatial resolution occurred markedly at the bottom surface of the specimen in the ADF-STEM but significantly less in the BF-STEM tomographic reconstruction. Our results indicate that it might be feasible to use BF-STEM tomography to determine the 3D structure of whole eukaryotic microorganisms prepared by freeze-substitution, embedding, and sectioning.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Monte Carlo electron-trajectory simulations in bright-field and dark-field STEM: Implications for tomography of thick biological sections

et al. 2009

View full text Add to dashboard Cite

show abstract

“…1 However, strong beam interactions such as multiple Rutherford and plasmon scattering cause significant decreases in image resolution with increasing specimen thickness. 2,3 Thus, to achieve good imaging conditions in a TEM/STEM requires extensive sample processing, i.e., thinning, to be performed.…”

mentioning

confidence: 99%

Submicron imaging of buried integrated circuit structures using scanning confocal electron microscopy

Frigo

Levine

Zaluzec

2002

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…One major argument in support of the STEM is the optimized detection strategy for picking the most sensitive signal as a function of thickness or composition variation, i.e. 'aperture' contrast, was theoretically and experimentally investigated by Crewe & Groves (1974), Reimer & Gentsch (1975) andSmith &Cowley (1975). In the first paper, the authors classify the different categories of electrons which pass through the specimen (unscattered, elastically scattered, inelastically scattered and mixed elastic-inelastic electrons) and calculate the contrast for various modes of illumination and detection in both conventional and scanning modes.…”

mentioning

confidence: 99%

“…In the first paper, the authors classify the different categories of electrons which pass through the specimen (unscattered, elastically scattered, inelastically scattered and mixed elastic-inelastic electrons) and calculate the contrast for various modes of illumination and detection in both conventional and scanning modes. In a subsequent publication, Groves (1975) evaluates the modulation transfer function (MTF) in the case of plural scattering and its associated resolution. As a consequence of the absence of chromatic aberration associated with the imaging lens, he estimates that a STEM operating at 100 keV would be equivalent to a CTEM at 1 MeV.…”

mentioning

confidence: 99%

Energy filtered STEM imaging of thick biological sections

Colliex

Mory

Olins

et al. 1989

Journal of Microscopy

View full text Add to dashboard Cite

Oak Ridge, TN 37830, U.S.A. KEY WORDS. STEM, energy filtered images, biological thick sections, EELS. S U M M A R YEnergy filtered imaging of thick biological specimens was analysed using a dedicated STEM fitted with an energy loss spectrometer and interfaced with a sophisticated data collection setup. All images were digital, thus permitting a quantitative analysis of the data. We also present a mathematical explanation of the data, which is useful in predicting the quality of thick specimen images formed with energy filtered electrons.It is known that increasing specimen thickness leads to a decrease of the zero energy loss intensity and an increase in higher (multiply scattered) energy loss electrons. We show that contrast decreases gradually with increased energy loss but, most important, the signal to noise ratio is maximal at an energy loss position slightly below the intensity maximum. This is the optimal position for imaging thick specimens. Moreover our studies confirm that the following parameters have similar effects on the energy loss spectra: (1) increased thickness (t); ( 2 ) higher average Z number elements (or lower mean free path Ai); and (3) lower primary voltage (VJ. I N T R O D U C T I O NCell biological organelles are usually asymmetric in three dimensions and traverse distances of several microns. Such structures must be studied by both light and electron microscopy in order to comprehend adequately their three-dimensional organization at various levels of resolution. Thick (i.e. 30.25 pm) embedded and stained sections present special problems to electron microscope imaging, The origin of the difficulties lies in the nature of the interaction process of the high energy primary electrons with the specimen. Both elastic and inelastic scattering cross-sections are relatively high (of the order of =lo-'* cmz) and consequently the mean free paths are short (typically = 100 nm for A, and A, in organic substances). As soon as the section thickness is of the order of a few hundred nanometres to the micron range, multiple scattering occurs so that the outgoing beam at the specimen exit surface is composed of a broad electron distribution both in energy (energy losses ranging to a few hundred electron volts) and in angle (scattering angles of a few tens to one hundred milliradians). The result is a degradation in intensity, contrast and resolution in an conventional mode where all these effects are combined as a net limitation in penetration power.In order to overcome this inherent penetration limit of electrons through matter, several solutions have been put foward and investigated over the last twenty years. The first is the use of higher primary voltages advocated by Dupouy (Dupouy, 1968;Dupouy et al., 1970;Favard et 0 1989 The Royal Microscopical Society 1 2 C. Colliex et al. al., 1971), with the Toulouse 1.2 and 3 MeV microscopes. They clearly demonstrated an increase in penetration power and an improvement in resolution for thick sections, due to the reduction in chromatic error. Since that time...

show abstract

Thick specimens in the CEM and STEM. Resolution and image formation

Cited by 54 publications

References 6 publications

Monte Carlo electron-trajectory simulations in bright-field and dark-field STEM: Implications for tomography of thick biological sections

Monte Carlo electron-trajectory simulations in bright-field and dark-field STEM: Implications for tomography of thick biological sections

Submicron imaging of buried integrated circuit structures using scanning confocal electron microscopy

Energy filtered STEM imaging of thick biological sections

Contact Info

Product

Resources

About