Field emission scanning electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 14-15
Author(s):  
R. Aihara ◽  
S. Saito ◽  
II. Kohinata ◽  
K. Ogura ◽  
H. Otsuji
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Probe Diameter ◽  
Tungsten Single Crystal ◽  
Working Distance ◽  
Scanning Electron

A compact type field emission scanning electron microscope (JSM-F15) has recently been developed (Fig. 1). Moreover, due to the simplicity of the electron optical column and the automatically controlled ultra high vacuum system, a good quality and high resolution image can easily be obtained.The electron optical column, which is shown in Fig. 2, comprises a field emission gun, an electromagnetic lens, scanning coils, etc. The gun, which is composed of a field emitter, a wehnelt and an anode, is pre-aligned. The accelerating voltage is 15 kV and the emitter tip, made of tungsten single crystal, has a [310] orientation in the electron optical axis. The wehnelt is biased through a feedback circuit so as to maintain the emission current constant without varying the accelerating voltage.The electron probe current at the specimen surface is about 3 × 10-11 amp and the probe diameter is about 30Å at the working distance of 15 mm.

scholarly journals Why Pressure Scales Cause So Much Confusion

1993 ◽  
Vol 1 (8) ◽  
pp. 5-6
Author(s):  
Anthony D. Buonaquisti
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Ambient Pressure ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Scanning Auger Microprobe ◽  
The Mean ◽  
Scanning Electron

Pressure scales can be extremely confusing to new operators. This is not surprising. To my mind, there are three primary areas of confusion.Firstly, the pressure of gas inside an instrument changes over many orders of magnitude during pumpdown. The change is about 9 orders of magnitude for a traditional Scanning Electron Microscope and about 13 orders of magnitude for an ultra-high vacuum instrument such as a Scanning Auger Microprobe.To give an idea about the scale of change involved in vacuum, consider that the change in going from ambient pressure to that inside a typical ultra high vacuum system is like comparing one meter with the mean radius of the planet Pluto's orbit. The fact is that we don't often get to play with things on that scale. As a consequence, many of us have to keep reminding ourselves that 1 X 10-3 is one thousand times the value of 1 X 10-6 - not twice the value.

The Observation of NBC Precipitates In Steels In The Nanometer Range Using A Field Emission Gun Scanning Electron Microscope

1997 ◽  
Vol 3 (S2) ◽  
pp. 1243-1244 ◽  
Author(s):  
Raynald Gauvin ◽  
Steve Yue
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Incident Electron Energy ◽  
Beam Diameter ◽  
Probe Diameter ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

The observation of microstructural features smaller than 300 nm is generally performed using Transmission Electron Microscopy (TEM) because conventional Scanning Electron Microscopes (SEM) do not have the resolution to image such small phases. Since the early 1990’s, a new generation of microscopes is now available on the market. These are the Field Emission Gun Scanning Electron Microscope with a virtual secondary electron detector. The field emission gun gives a higher brightness than those obtained using conventional electron filaments allowing enough electrons to be collected to operate the microscope with incident electron energy, E0, below 5 keV with probe diameter smaller than 5 nm. At 1 keV, the electron range is 60 nm in aluminum and 10 nm in iron (computed using the CASINO program). Since the electron beam diameter is smaller than 5 nm at 1 keV, the resolution of these microscopes becomes closer to that of TEM.

scholarly journals Why Pressure Scales Cause So Much Confusion

2001 ◽  
Vol 9 (1) ◽  
pp. 26-27
Author(s):  
Anthony D. Buonaquisti
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Auger Microprobe ◽  
Scanning Electron

Pressure scales can be extremely confusing to new operators. This is not surprising. To my mind, there are three primary areas of confusion.Firstly, the pressure of gas inside an instrument changes over many orders of magnitude during pump-down. The change is about 9 orders of magnitude for a traditional Scanning Electron Microscope and about 13 orders of magnitude for an ultra-high vacuum instrument such as a Scanning Auger Microprobe.

Novel Morphology of Voids in Single-Quasicrystalline Icosahedral Al70.5Pd21.0Mn8.5

1998 ◽  
Vol 53 (8) ◽  
pp. 679-683 ◽  
Author(s):  
Y. Waseda ◽  
S. Suzuki ◽  
K. Urbanb
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Surface Composition ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Chemical Surface ◽  
Habit Planes ◽  
Scanning Electron

Abstract This paper deals with the morphology and surface chemistry of faceted voids existing in singlequasicrystalline icosahedral Al70.5Pd21.0Mn8.5. By observation with a scanning electron microscope of surfaces obtained by cleavage of the quasicrystal, the habit planes of the dodecahedral voids were identified. The chemical surface composition of the void surface was determined by Auger electron spectroscopy after cleavage in ultra-high vacuum.

Electron back-scattering patterns in a field emission gun scanning electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 564-565
Author(s):  
C.J. Harland ◽  
J.H. Klein ◽  
P. Akhter ◽  
J.A. Venables
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Polycrystalline Material ◽  
High Vacuum ◽  
Spot Size ◽  
Ultra High Vacuum ◽  
Scattering Pattern ◽  
Fluorescent Screen ◽  
Back Scattering ◽  
Scanning Electron

INTRODUCTION.The electron back-scattering pattern (EBSP) is a simple means of obtaining the crystallographic orientation of samples in the SEM. Kikuchi bands are observed on a fluorescent screen ∼15mm in front of a (tilted) sample /l/ and shadows, for example of three spherical balls, can be used to obtain orientation determinations accurate to ± 0. 5° /2/. We have also shown that a fibre-optic detector of angular diameter <2θB can be used to form images of polycrystalline material with markedly increased grain contrast /3/.In the present paper we report that these techniques have been transferred onto an ultra-high vacuum SEM equipped with a field emission gun (FEG). The higher brightness of the FEG enables the spot size to be reduced markedly. The transition between the orientation of one grain and the next has been shown to be as sharp as 50nm. Shifts due to sub-grain boundaries down to ∼1° can be readily seen

A High Vacuum Scanning Electron Microscope

1972 ◽  
Vol 30 ◽  
pp. 422-423
Author(s):  
W. R. Bottoms
Keyword(s):  
Electron Microscope ◽  
Chemical Composition ◽  
Scanning Electron Microscope ◽  
High Vacuum ◽  
Electron Source ◽  
Electron Gun ◽  
Vacuum System ◽  
Contamination Rate ◽  
Time Required ◽  
Scanning Electron

The vacuum system of any electron optical instrument effects the contamination rate, electron source life, the quality of the electron source which can be employed, vibration amplitudes and stray magnetic field levels. It is particularly important for the scanning electron microscope where the object of primary interest is a specimen surface which can be altered by contamination. If we extend our investigations to employ Auger electron spectroscopy for surface chemical analysis, the requirements on the vacuum system are much more stringent. It is necessary that the chemical composition of the surface monolayer is not appreciably altered during the time required to take Auger spectra. The vacuum level required to accomplish this is dependent on the specimen material and the chemical composition of the ambient gas.Commercially available equipment can be modified to provide a vacuum environment maximizing the analytical capabilities of the instrument. The gas loads from the specimen and electron gun chambers of the instrument are minimized by utilizing only materials with favorable outgassing rates, and employing a gentle bakeout to remove water and other loosely bound gases on the system surfaces.

Use of platinum shadowing and magnetron sputter coating in an Oxford Cryotrans system to increase low temperature resolution of biological samples in a Hitachi field-emission Scanning Electron Microscope

1993 ◽  
Vol 51 ◽  
pp. 122-123
Author(s):  
William P. Wergin ◽  
Eric F. Erbe ◽  
Alan Robins
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
High Vacuum ◽  
Water Ice ◽  
Temperature Observation ◽  
Sputter Coating ◽  
Magnetron Sputter ◽  
Scanning Electron

Previous studies in this laboratory have shown that the resolution of biological specimens could be increased at least two fold in a conventional as well as a field emission SEM by substituting high vacuum evaporation of Pt for standard sputter coating. Because the EMscope SP2000A Sputter Cryo System and the Oxford CT 1500 Cryotrans System, which were used in these experiments, employed standard sputter coating, Pt shadowing and C evaporation were carried out in a modified Denton DFE-3 freeze-etch module on a DV-503 high vacuum evaporator and the coated specimens were transferred to the cryostage (EMscope) or the prechamber (Oxford) of the cryosystem. Not only did this procedure require a high vacuum evaporator but as a result of a through air transfer into LN2, considerable contamination condensed on the surface of the specimen. Most of this contamination consisted of water ice that could be easily sublimed; however, other unidentifiable contaminants remained. To increase the versatility of the cryosystem, reduce surface contamination of the specimen and evaluate alternative coating procedures, Oxford Cryotrans Systems were equipped and tested with a Pt evaporator and a high resolution magnetron sputter head. Low temperature observation and evaluation of the coated specimens were performed in a Hitachi S4100 field emission scanning electron microscope.

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