A standard organic sample for evaluating the imaging capabilities of Scanning Electron Microscopes

1994 ◽  
Vol 52 ◽  
pp. 1020-1021
Author(s):  
Patrick Echlin
Keyword(s):  
Noble Metals ◽  
Pollen Grains ◽  
Polystyrene Spheres ◽  
Medical Laboratories ◽  
Organic Sample ◽  
Digital Scanning ◽  
Electron Microscopes ◽  
Beam Currents ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

We have been evaluating several digital scanning electron microscopes prior to the eventual purchase of an instrument. Most manufacturers demonstrate the capabilities of their instruments by using test specimens such as ultra-thin films of sputtered or evaporated noble metals, semi-conductors and photo resists and highly polished multi-compositional specimens made up of light and heavy elements. The microscope we need will be used for imaging and analysis by people from bio-medical laboratories and we are particularly interested in the quality of images we can obtain at low voltages and low beam currents from uncoated and coated samples and whether the specimens suffer any contamination and beam damage during examination and analysis. We do not envisage working at accelerating voltages much above 15keV. We needed a standard organic sample which was stable and easy to prepare and representative of the type of material we would be examining in the microscope we will eventually purchase. After investigating polystyrene spheres and a number of more natural bio-organic samples, including coffee creamer, starch, flour, pollen grains and spores we discovered that spray dried milk is an ideal sample to use for these instrumental evaluations.

scholarly journals Pollen morphology of some Turkish Campanula spp. and their taxonomic value

1970 ◽  
Vol 37 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Ismuhan Potoglu Erkara ◽  
Atila Ocak ◽  
Sevil Pehlivan
Keyword(s):  
Key Words ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Exine Sculpture ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
First Time ◽  
Scanning Electron

Detailed pollen morphological structures of 12 Turkish species of Campanula L., e.g. C. argaea, C. cymbalaria, C. glomerata subsp. hispida, C. latiloba subsp. latiloba, C. lyrata subsp. lyrata, C. olympica, C. persicifolia, C. pterocaula, C. rapunculoides subsp. cordifolia, C. rapunculus var. rapunculus, C. stricta var. stricta, C. pamphylica subsp. tokurii have been studied under light (LM) and scanning electron microscopes (SEM) for the first time. LM and SEM investigations show that the pollen grains of 12 taxa are more or less oblato-sphaeroidal, triporate (and/or tetraporate), tectum-scabrate, or with circular amb. The exine sculpture is granulate-scabrate in C. argaea, C. lyrata subsp. lyrata, C. stricta var. stricta, C. glomerata subsp. hispida and C. pamphylica subsp. tokurii; but those of C. cymbalaria, C. latiloba subsp. latiloba, C. olympica, C. persicifolia, C. pterocaula, C. rapunculoides subsp. cordifolia and C. rapunculus var. rapunculus are rugulate-scabrate.   Key words: Campanula, Pollen grains, Pollen morphology doi:10.3329/bjb.v37i1.1561 Bangladesh J. Bot. 37(1): 33-42, 2008 (June)

A digital scanning Auger electron microscope incorporating a concentric hemispherical analyser

1977 ◽  
Vol 357 (1689) ◽  
pp. 213-230 ◽  
Keyword(s):  
Electron Microscope ◽  
Electron Gun ◽  
Resolving Power ◽  
Electrostatic Lenses ◽  
Different Types ◽  
Digitally Controlled ◽  
Digital Scanning ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

A scanning electron microscope with a field-emitting electron gun, digitally controlled scanning and a concentric hemispherical energy analyser is described and compared with different types of energy dispersive scanning electron microscopes. The advantages of hemispherical analysers accessed by electrostatic lenses are flexible electron optical control of working distances and resolving power. A 4 element lens is described which results in an analyser with a 2 eV window over an energy range of 20 eV to 800 eV. Auger images of calcium and sulphur on titanium are given. Spatial resolutions of 50 nm and frame scan times of a few minutes are possible.

scholarly journals Pollen morphology of some Turkish Ajuga L. (Lamiaceae) and its taxonomic value

1970 ◽  
Vol 40 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Yavuz Bulent Kose ◽  
Ismahan Potoglu Erkara ◽  
Sevim Alan
Keyword(s):  
Key Words ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Exine Sculpture ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
First Time ◽  
Scanning Electron

Pollen morphological structures of eight Turkish species of Ajuga, namely A. bombycina Boiss., A. chamaepitys (L.) Schreber ssp. chia var. chia (Schreber) Arcangeli, A. chamaepitys (L.) Schreber ssp. chia var. ciliata Briq., A. chamaepitys (L.) Schreber ssp. cuneatifolia (Stapf) P. H. Davis, A. genevensis L., A. laxmannii (L.) Benthum, A.orientalis L. and A. reptans L. have been studied under light and scanning electron microscopes for the first time. It is revealed that the pollen grains of Ajuga taxa are more or less suboblata-subprolata and tricolpatae. The exine sculpture is granulate in A. chamaepitys subsp. chia var. chia, A. chamaepitys subsp. cuneatifolia, A. genevensis, A. laxmannii, A. orientalis and A. reptans, but it is reticulate in A. bombycina and A. chamaepitys subsp. chia var. ciliata. Key words: Turkish Ajuga; Pollen morphology; Taxonomic value DOI: http://dx.doi.org/10.3329/bjb.v40i1.7994 Bangladesh J. Bot. 40(1): 29-33, 2011 (June)

Texture and Artifacts in SEM Observations Due to Vapor Coating

1972 ◽  
Vol 30 ◽  
pp. 406-407
Author(s):  
G. G. Paulson ◽  
R. W. Pierce
Keyword(s):  
Electron Microscopy ◽  
Noble Metals ◽  
Specimen Preparation ◽  
Polystyrene Spheres ◽  
Final Thickness ◽  
Quantitative Measurements ◽  
Glass Slides ◽  
Beam Currents ◽  
Preparation Techniques ◽  
Scanning Electron

Specimen preparation techniques for scanning electron microscopy have not necessarily kept pace with the advances in instrumentation, especially in fields where quantitative measurements are important. Even though many operators have found that nonconducting surfaces can often be examined directly with low voltages and small beam currents, most commonly these surfaces are vapor-coated with 100 to 600 A of a noble metal alloy. More often than not, the coating procedures involve a bit of guesswork as to the final thickness and structure of the vapor coating. The purpose of this research was to illustrate the importance of close control on coating thickness and uniformity in order to minimize artifacts and distortion. Several noble metals and alloys were studied. The results for gold coatings are reported.Polystyrene spheres of statistically uniform diameters were dispersed on glass slides. The slides were rotated as they were coated by thermal deposition of Au from a W boat at a pressure of 2 x 10-5 torr in a standard oil diffusion pumped vapor coater.

scholarly journals Palynological features of eleven Aethionema taxa from Turkey and their systematic implications

2017 ◽  
Vol 24 (2) ◽  
pp. 197-204 ◽  
Author(s):  
Mehmet Cengiz Karaismailoglu
Keyword(s):  
Pollen Morphology ◽  
Pollen Grains ◽  
Plant Taxon ◽  
Surface Ornamentation ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Pollen morphology of 11 taxa, including 2 endemic of the genus Aethionema W.T. Aiton from Turkey was examined under light and scanning electron microscopes. The pollens of Aethionema are mostly isopolar and bilaterally symmetric; spheroidal, prolate, perprolate and subprolate with the polar axes 14.07-26.41 μm and the equatorial axes 7.85-22.02 μm; mostly tricolpate, rarely 2-colpate; surface ornamentation is micro or macro reticulate. The exine thickness varies between 0.66 and 1.91 μm, and in tine thickness ranges from 0.27 to 0.85 μm. It is found that dimension of pollen grains, surface ornamentation, apocolpidium and amb diameter are taxonomically significant.Bangladesh J. Plant Taxon. 24(2): 197-204.

Current State of Biological High-Resolution Scanning Electron Microscopy

1988 ◽  
Vol 46 ◽  
pp. 180-181 ◽  
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Performance ◽  
Low Voltage ◽  
Backscattered Electrons ◽  
Lens Position ◽  
Low Voltage Operation ◽  
Signal Collection ◽  
Probe Size ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

A new generation of high performance field emission scanning electron microscopes (FSEM) is now commercially available (JEOL 890, Hitachi S 900, ISI OS 130-F) characterized by an "in lens" position of the specimen where probe diameters are reduced and signal collection improved. Additionally, low voltage operation is extended to 1 kV. Compared to the first generation of FSEM (JE0L JSM 30, Hitachi S 800), which utilized a specimen position below the final lens, specimen size had to be reduced but useful magnification could be impressively increased in both low (1-4 kV) and high (5-40 kV) voltage operation, i.e. from 50,000 to 200,000 and 250,000 to 1,000,000 x respectively.At high accelerating voltage and magnification, contrasts on biological specimens are well characterized1 and are produced by the entering probe electrons in the outmost surface layer within -vl nm depth. Backscattered electrons produce only a background signal. Under these conditions (FIG. 1) image quality is similar to conventional TEM (FIG. 2) and only limited at magnifications >1,000,000 x by probe size (0.5 nm) or non-localization effects (%0.5 nm).

Observation of GaAs/AlAs Superlattice Structures in both Secondary and Backscattcred Electron Imaging Modes with an Ultrahigh Resolution Scanning Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 404-405
Author(s):  
K. Ogura ◽  
A. Ono ◽  
S. Franchi ◽  
P.G. Merli ◽  
A. Migliori
Keyword(s):  
Gaas Layer ◽  
Objective Lens ◽  
Superlattice Structure ◽  
Backscattered Electron ◽  
Instrumental Resolution ◽  
Electron Microscopes ◽  
Superlattice Structures ◽  
Electron Imaging ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

In the last few years the development of Scanning Electron Microscopes (SEM), equipped with a Field Emission Gun (FEG) and using in-lens specimen position, has allowed a significant improvement of the instrumental resolution . This is a result of the fine and bright probe provided by the FEG and by the reduced aberration coefficients of the strongly excited objective lens. The smaller specimen size required by in-lens instruments (about 1 cm, in comparison to 15 or 20 cm of a conventional SEM) doesn’t represent a serious limitation in the evaluation of semiconductor process techniques, where the demand of high resolution is continuosly increasing. In this field one of the more interesting applications, already described (1), is the observation of superlattice structures.In this note we report a comparison between secondary electron (SE) and backscattered electron (BSE) images of a GaAs / AlAs superlattice structure, whose cross section is reported in fig. 1. The structure consist of a 3 nm GaAs layer and 10 pairs of 7 nm GaAs / 15 nm AlAs layers grown on GaAs substrate. Fig. 2, 3 and 4 are SE images of this structure made with a JEOL JSM 890 SEM operating at an accelerating voltage of 3, 15 and 25 kV respectively. Fig. 5 is a 25 kV BSE image of the same specimen. It can be noticed that the 3nm layer is always visible and that the 3 kV SE image, in spite of the poorer resolution, shows the same contrast of the BSE image. In the SE mode, an increase of the accelerating voltage produces a contrast inversion. On the contrary, when observed with BSE, the layers of GaAs are always brighter than the AlAs ones , independently of the beam energy.

Pollen morphology of some Tamarix (Tamaricaceae) species of Iran

2020 ◽  
Vol 62 (1-2) ◽  
pp. 151-161
Author(s):  
T. Shagholi ◽  
M. Keshavarzi ◽  
M. Sheidai
Keyword(s):  
North Africa ◽  
Pollen Grains ◽  
Ecological Niches ◽  
Multivariate Statistical Methods ◽  
Multivariate Statistical ◽  
Qualitative And Quantitative ◽  
Petal Length ◽  
Electron Microscopes ◽  
High Level ◽  
Scanning Electron Microscopes

Tamarix L. (Tamaricaceae) is a halophytic shrub in different parts of Asia and North Africa. Taxonomy and species limitation of Tamarix is very complex. This genus has three sections as Tamarix, Oligadenia, and Polyadenia, which are mainly separated by petal length, the number of stamens, the shape of androecial disk and attachment of filament on the androecial disk. As there was no palynological data on pollen features of Tamarix species of Iran, in the present study 12 qualitative and quantitative pollen features were evaluated to find diagnostic ones. Pollen grains of 8 Tamarix species were collected from nature. Pollen grains were studied without any treatment. Measurements were based on at least 50 pollen grains per specimen. Light and scanning electron microscopes were used. Multivariate statistical methods were applied to clarify the species relationships based on pollen data. All species studied showed monad and tricolpate (except some individuals of T. androssowii). Some Tamarix species show a high level of variability, in response to ecological niches and phenotypic plasticity, which make Tamarix species separation much more difficult. Based on the results of the present study, pollen grains features are not in agreement with previous morphological and molecular genetics about the sectional distinction.

Discoasters of the Blue Clay (Middle Miocene) of Malta and Gozo

1978 ◽  
Vol 115 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Minoo Hojjatzadeh
Keyword(s):  
Middle Miocene ◽  
The Family ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

SummaryTwenty-three species of the Family Discoasteraceae Vekshina, 1959 recovered from 18 samples of the Blue Clay at Fort Chambray, Gozo, and 31 samples from Fomm-Ir-Rih Bay, Malta, have been studied under light and scanning electron microscopes. Fourteen Middle Miocene species are reviewed, their stratigraphical ranges and importance as marker species discussed. Nine species are described as new. On the basis of the discoaster species present, a Middle Miocene age (NN.6 Discoaster exilis Zone – NN.7 Discoaster kugleri Zone) for the Blue Clay in Malta and Gozo is suggested.

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