scholarly journals High-Resolution Imaging of Dried and Living Single Bacterial Cell Surfaces: Artifact or Not?

2011 ◽  
Vol 19 (5) ◽  
pp. 22-25 ◽  
Author(s):  
Dominik Greif ◽  
Daniel Wesner ◽  
Dario Anselmetti ◽  
Jan Regtmeier
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Metal Coating ◽  
Environmental Scanning ◽  
Cell Surfaces ◽  
Critical Point Drying ◽  
Resolution Imaging ◽  
Sem Imaging ◽  
Scanning Electron

When studying highly resolved scanning electron microscope images of cell surfaces, the question arises, whether the observed patterns are real or just artifacts of the cell preparation process. The following steps are usually necessary for preparation: fixation, drying, and metal coating. Each step might introduce different artifacts. Clever techniques have been developed to dry cells as gently as possible, for example critical point drying with different organic solvents and CO2. Instrument manufacturers also have taken account of this issue, for example, through the realization of the environmental scanning electron microscope (ESEM), operating with a low-vacuum environment saturated with water so that samples might stay hydrated. Another approach is the extreme high-resolution scanning electron microscope (XHR SEM), where the electron beam is decelerated shortly before reaching the sample. This technique requires no metal coating of the sample. Cryo-SEM also may be used, where no sample preparation is required beyond freezing in a high-pressure freezer or other cryo-fixation device. Then the cell can be examined in the frozen, hydrated state using a cryostage. However, at least some kind of preparation is necessary for SEM imaging, and we wanted to find out what changes the preparation makes on the cell surface.

FIB Enhancement of Mechanically Polished Cross-sections

2019 ◽  
Author(s):  
Becky Holdford
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
High Resolution Imaging ◽  
Chemical Attack ◽  
Resolution Imaging ◽  
Scanning Electron

Abstract On mechanically polished cross-sections, getting a surface adequate for high-resolution imaging is sometimes beyond the analyst’s ability, due to material smearing, chipping, polishing media chemical attack, etc.. A method has been developed to enable the focused ion beam (FIB) to re-face the section block and achieve a surface that can be imaged at high resolution in the scanning electron microscope (SEM).

Reduction of contamination using a specimen heating holder in an ultra high resolution Scanning Electron Microscope

1989 ◽  
Vol 47 ◽  
pp. 724-725
Author(s):  
K. Ogura ◽  
A. Ono ◽  
M. M. Kersker
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Electron Probe ◽  
Carbon Film ◽  
Specimen Surface ◽  
Gas Molecules ◽  
Sem Imaging ◽  
Coated Carbon ◽  
Scanning Electron

In general, various improvements have been made to SEM vacuum systems, and clean high vacuum specimen chambers are now routinely available. However, in the ultra high resolution scanning electron microscope, the prevention or reduction of contamination on the specimen surface has recently become an important subject when SEM imaging is done at higher than 200,000x magnification using a very fine electron probe. Typically, the specimen carries hydrocarbon gas molecules which are the source of the contamination, into the SEM. They adhere not only to the specimen surface but may also incorporated in the specimen, most typically in biological specimens, and cannot be reduced by the anti-contamination device of the SEM. Recently, a specimen heating holder was used in a JSM-890 ultra high resolution SEM, to reduce the contamination deposition on the specimen surface during SEM imaging. Using this holder, the specimen can be heated up to 300°C inside the SEM. Images 1 to 4 in Fig. 1 are the secondary electron images showing the cone-shaped deposition of contamination on a platinum-coated carbon film at different heating temperatures. This platinum-coated film, which had been kept in wet and oily atmosphere for several weeks to insure it was well covered with hydro carbon gas molecules, was irradiated by an electron probe in a spot mode for 30sec. with 1×10−11 Amp. of probe current at 20kV. After the electron probe irradiation, the platinum-coated carbon film was tilted 45° for imaging. Image 1 in Fig. 1 shows the cone-shaped deposition of contamination when the specimen was not heated. Image 2 was at 35°C, Image 3 was at 55°C, and Image 4 in Fig. 1 was at 115°C. At higher than 120°C specimen heating temperature, the cone-shaped deposition of contamination could not be observed any more. On the other hand, we can heat up the specimen outside the SEM before we put the specimen into the SEM. Image 5 in Fig. 1 shows the results of specimen heating by a hair dryer. The same platinum- coated carbon film was heated by a hair dryer for 1 minute before it was intro- duced into the SEM, and was irradiated by the electron probe for 15, 30, and 45sec. in a spot mode. This 1 min. heating by a hair dryer shows almost same result as 55°C specimen heating in the SEM.

A Miniature Low Voltage SEM with High Resolution

1999 ◽  
Vol 5 (S2) ◽  
pp. 322-323
Author(s):  
J.M. Krans ◽  
T.L. van Rooy
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Low Voltage ◽  
Optical Systems ◽  
Objective Lens ◽  
Secondary Electrons ◽  
Voltage Imaging ◽  
Resolution Imaging ◽  
Scanning Electron

Miniaturization of electron optical systems has gained much interest over the last decade [1,2]. In a scanning electron microscope, downscaling of the column dimensions is expected to allow for high resolution imaging at low electron beam voltage. Main advantages of low voltage imaging are lower penetration depth, increased secondary electron yield, less specimen charging and better topographic contrast [3].We have developed a miniature scanning electron microscope (SEM) with high resolution at low beam energies. The outer dimensions of the miniaturized SEM column are 25 mm diameter and 95 mm length, including conventional field emitter electron source module. The column prototype is shown in Fig. 1. The size reduction has been achieved by the exclusive implementation of electrostatic column components. Electron optical simulations indicate that the retarding objective lens of the miniature SEM allows for a probe resolution of 3 nm at 1 keV beam energy. The secondary electrons are collected at an internal scintillator detector.

scholarly journals A Study on Biological Sample Preparation for High Resolution Imaging of Scanning Electron Microscope

2020 ◽  
Vol 1447 ◽  
pp. 012034
Author(s):  
Siti Rahmah Aid ◽  
Nik Nur Anis Awadah Nik Zain ◽  
Nur Nadhirah Mohd Rashid ◽  
Hirofumi Hara ◽  
Kamyar Shameli ◽  
...  
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Sample Preparation ◽  
Biological Sample ◽  
High Resolution Imaging ◽  
Resolution Imaging ◽  
Scanning Electron

Field Emission SEM Equipped With Noise Compensator

1973 ◽  
Vol 31 ◽  
pp. 302-303
Author(s):  
S. Saito ◽  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Low Contrast ◽  
Probe Current ◽  
High Resolution Images ◽  
Scanning Electron

Field emission scanning electron microscope (FESEM) features extremely high resolution images, and offers many valuable information. But, for a specimen which gives low contrast images, lateral stripes appear in images. These stripes are resulted from signal fluctuations caused by probe current noises. In order to obtain good images without stripes, the fluctuations should be less than 1%, especially for low contrast images. For this purpose, the authors realized a noise compensator, and applied this to the FESEM.Fig. 1 shows an outline of FESEM equipped with a noise compensator. Two apertures are provided gust under the field emission gun.

High Resolution Scanning Electron Microscopy

1991 ◽  
Vol 49 ◽  
pp. 478-479
Author(s):  
David Joy ◽  
James Pawley
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Electron Probe ◽  
Impact Point ◽  
Interaction Volume ◽  
Scanning Electron

The scanning electron microscope (SEM) builds up an image by sampling contiguous sub-volumes near the surface of the specimen. A fine electron beam selectively excites each sub-volume and then the intensity of some resulting signal is measured. The spatial resolution of images made using such a process is limited by at least three factors. Two of these determine the size of the interaction volume: the size of the electron probe and the extent to which detectable signal is excited from locations remote from the beam impact point. A third limitation emerges from the fact that the probing beam is composed of a finite number of discrete particles and therefore that the accuracy with which any detectable signal can be measured is limited by Poisson statistics applied to this number (or to the number of events actually detected if this is smaller).

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