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

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.

A Field Emission System For Transmission Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 298-299
Author(s):  
Michel Troyonal ◽  
Huei Pei Kuoal ◽  
Benjamin M. Siegelal
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Optical System ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Objective Lens ◽  
Electron Optical System ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Emission System

A field emission system for our experimental ultra high vacuum electron microscope has been designed, constructed and tested. The electron optical system is based on the prototype whose performance has already been reported. A cross-sectional schematic illustrating the field emission source, preaccelerator lens and accelerator is given in Fig. 1. This field emission system is designed to be used with an electron microscope operated at 100-150kV in the conventional transmission mode. The electron optical system used to control the imaging of the field emission beam on the specimen consists of a weak condenser lens and the pre-field of a strong objective lens. The pre-accelerator lens is an einzel lens and is operated together with the accelerator in the constant angular magnification mode (CAM).

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 Energy Spectra of Secondary Electrons

2000 ◽  
Vol 6 (S2) ◽  
pp. 750-751
Author(s):  
David C Joy ◽  
David Braski
Keyword(s):  
Surface Layer ◽  
Electron Microscope ◽  
Secondary Electron ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Energy Spectra ◽  
Yield Coefficient ◽  
Sem Images ◽  
Secondary Electrons ◽  
Scanning Electron

It has been estimated that more than 90% of all scanning electron microscope (SEM) images ever published have been obtained using secondary electrons (SE) which are defined as being those electrons emitted with energies between 0 and 50eV. The properties of these secondary electron are therefore of considerable interest and importance. However, although secondary electrons have been intensively studied since their discovery by Starke in 1901 the majority of the work has been aimed at determining the SE yield coefficient and its variation with energy for elements and compounds. The energy spectrum of secondary electrons has received far less attention although it is evident that the form of the spectrum must have an effect on the image contrast observed in the SEM because SE detectors are energy selective devices. The few studies that have been made have mostly concentrated on spectra obtained from clean samples observed under ultra-high vacuum conditions. This is understandable, because it is certain that the presence of a surface layer of contamination will change the SE spectrum to some degree or other, but it is unfortunate because all specimens in real SEMs are dirty and it is information about this situation that is required.

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.

A Field Emission Electron Microscope

1971 ◽  
Vol 29 ◽  
pp. 6-7
Author(s):  
A. Tonomura ◽  
T. Komoda
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
High Vacuum ◽  
High Resolution Electron Microscopy ◽  
Ultra High Vacuum ◽  
Electron Optics ◽  
Ion Pumps ◽  
High Brightness ◽  
Emission Electron ◽  
Resolution Electron

We have developed a field emission electron microscope. Although field emission gun requires ultra high vacuum and skillful technique, it brings about the favorable characteristics of high brightness and small energy spread. This characteristics will enable a significant progress in coherent electron optics and high resolution electron microscopy, especially in electron beam holography.Its column is Hitachi HU-11C Electron Microscope modified for ultra high vacuum operation, and it is evacuated with five ion pumps. Field emission gun is divided into two parts and is evacuated differentially with two ion pumps and a sublimation pump. The final pressures in these rooms are 5x10-10 Torr and 5x10-8 Torr respectively.

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