Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

Development of the Cryo Pump System for Electron Microscope

1981 ◽  
Vol 39 ◽  
pp. 386-387
Author(s):  
M. Iwatsuki ◽  
Guy Venuti
Keyword(s):  
Electron Microscope ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Ion Pumps ◽  
Pump System ◽  
Electron Microscopes ◽  
Vacuum Systems ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

In proportion, as the electron microscope expands the field as an analytical instrument, the problems of specimen contaimination will become more critical. Also, emission instability and short life of the LaB6 tips depend on the ultimate vacuum pressure in the gun chamber (particularly, due to the partial pressure of oxygenized molecules). Meanwhile, as scanning electron microscopes are utilized as a means for quality control in the semi-conductor field, as well as for analysis, the problems with specimen contamination will become more prominent.Today, DP-RP type pumps are widely used as high vacuum pumps in scanning electron microscopes. However, due to the oil used in these pumps, back-streaming occurs, causing specimen contamination. In contrast to this wet vacuum system, ion pumps, Ti-sublimation pumps, and Turbo-molecular pumps, etc. have been utilized as dry vacuum systems. Among these dry pumps, ion pumps and Ti-sublimation pumps are most popular as a means of obtaining ultra high vacuum. Also, Turbo-molecular pumps are widely used for scanning electron microscopes.

A Freeze Shadow Technique for the Preparation of Soft Paint Latexes for Electron Microscopy

1977 ◽  
Vol 35 ◽  
pp. 314-315
Author(s):  
Earl R. Walter ◽  
Glen H. Bryant
Keyword(s):  
Sample Preparation ◽  
High Vacuum ◽  
Vacuum System ◽  
Latex Particles ◽  
New Methods ◽  
Diffusion Pump ◽  
Film Forming ◽  
Routine Basis ◽  
Distribution Studies ◽  
Preparation Techniques

With the development of soft, film forming latexes for use in paints and other coatings applications, it became desirable to develop new methods of sample preparation for latex particle size distribution studies with the electron microscope. Conventional latex sample preparation techniques were inadequate due to the pronounced tendency of these new soft latex particles to distort, flatten and fuse on the substrate when they dried. In order to avoid these complications and obtain electron micrographs of undistorted latex particles of soft resins, a freeze-dry, cold shadowing technique was developed. The method has now been used in our laboratory on a routine basis for several years.The cold shadowing is done in a specially constructed vacuum system, having a conventional mechanical fore pump and oil diffusion pump supplying vacuum. The system incorporates bellows type high vacuum valves to permit a prepump cycle and opening of the shadowing chamber without shutting down the oil diffusion pump. A baffeled sorption trap isolates the shadowing chamber from the pumps.

PHAX-SCAN: Functional integration of a Scanning Electron Microscope and an energy-dispersive x-ray analyser

1989 ◽  
Vol 47 ◽  
pp. 56-57
Author(s):  
Marc H. Peeters ◽  
Max T. Otten
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
Functional Integration ◽  
Energy Dispersive ◽  
X Rays ◽  
X Ray ◽  
High Speed Analysis ◽  
Scanning Electron

Over the past decades, the combination of energy-dispersive analysis of X-rays and scanning electron microscopy has proved to be a powerful tool for fast and reliable elemental characterization of a large variety of specimens. The technique has evolved rapidly from a purely qualitative characterization method to a reliable quantitative way of analysis. In the last 5 years, an increasing need for automation is observed, whereby energy-dispersive analysers control the beam and stage movement of the scanning electron microscope in order to collect digital X-ray images and perform unattended point analysis over multiple locations.The Philips High-speed Analysis of X-rays system (PHAX-Scan) makes use of the high performance dual-processor structure of the EDAX PV9900 analyser and the databus structure of the Philips series 500 scanning electron microscope to provide a highly automated, user-friendly and extremely fast microanalysis system. The software that runs on the hardware described above was specifically designed to provide the ultimate attainable speed on the system.

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.

Ion Pumped Vacuum System for the 500 kV University of Virginia Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 272-273
Author(s):  
J. H. Reisner ◽  
S. W. Shapiro ◽  
K. R. Lawless
Keyword(s):  
Electron Microscope ◽  
Vacuum System ◽  
Ion Pump ◽  
Ion Pumps ◽  
University Of Virginia ◽  
Short Life ◽  
Diffusion Pump ◽  
Column Design ◽  
Ion Pumping ◽  
Conventional Type

Contemporary microscope design does not lend itself well to ion pumping because of its commitment to the use of many elastomer gaskets with high gas loading. This leads to little change in partial pressure of contaminants and short life of pump elements when ion pumps are merely substituted for oil pumps. With the use of an ion-pumped accelerator on the "Virginia” microscope, and a new column design to minimize gas load, it appeared logical to use an ion pump for the rest of the system. Such a step can only be really successful if the column can be rough-pumped to about 10−4 Torr or better, and if the bulk of the gas load from the photomaterials is not removed by the column ion pump. Prepumping to remove this load is only partially effective if carried on separately from the microscope. Therefore a diffusion pump was added to a conventional type photo loading chamber, so that photomaterials can be introduced directly into the microscope after they have been pumped to pressure of 10−5 − 10−6 Torr which is far below conventional practice.

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.

Improvements & Performance of the Hitachi 200KV Electron Microscope

1968 ◽  
Vol 26 ◽  
pp. 306-307
Author(s):  
S. Katagiri ◽  
H. Akahori ◽  
S. Ueno ◽  
A. Iwama
Keyword(s):  
Electron Microscope ◽  
High Vacuum ◽  
High Capacity ◽  
Electron Gun ◽  
Inert Gases ◽  
Vacuum System ◽  
Surface Discharge ◽  
List Type ◽  
Free System ◽  
Chamber Volume

1.Electron gun - A new high voltage cable and porcelain insulator has been developed. A successful study of superior surface treatment of the insulator and improved means of sealing the cable resulted in eliminating surface discharge of the insulator. Since an electrode discharge and surface discharge of an insulator cannot be completely eliminated in a vacuum of the order of 10-5 to 10-6 torr, an high capacity vacuum system is employed to assure high vacuum and a discharge free system. Further, small quantities of inert gases such as N2, Ar, He etc. is introduced into the gun chamber to maintain a vacuum of 1 to 2 x 10-4 torr.2.Evacuating system.At 200KV it is necessary in a single stage electron gun to provide greater insulating distance to inhibit discharges. Consequently, the electron gun chamber is inevitably larger. The gun chamber volume of this electron microscope is 32 liter. A 4″ diameter single manifold and 1200 liter/sec. oil diffusion pump comprise the evacuating system.

scholarly journals History of High Vacuum and Critical Point Equipment used in EM Specimen Preparation

1993 ◽  
Vol 1 (7) ◽  
pp. 3-3
Author(s):  
Richard A. Denton
Keyword(s):  
United States ◽  
Electron Microscope ◽  
High Vacuum ◽  
Mean Free Path ◽  
The United States ◽  
Specimen Preparation ◽  
Vacuum Technology ◽  
Diffusion Pump ◽  
History Of ◽  
The Mean

The electron microscope was only possible with the development of high vacuum technology. Mechanical pumps were available early in this century, and Gaede in Germany developed the mercury pump called a “condensation pump” during WWI and in the 1920's. In 1928, Burch in England found that a low vapor pressure oil would work in a mercury pump and the oil diffusion pump was born. They were made by DPI in Rochester, Metropolitan Vickers in England, and Leyboid in Germany. Other oils became available and in the mid-30's, vacuum evaporators were in laboratory use in England, Germany and the United States.In the 1930's and 40's, the aim was to produce vacuum of 10-4 - 10-5 mm Hg where the mean free path was two feet or more and atoms, molecules and electrons could move this distance with little obstruction. In those days, we were all very happy to get 10-4 - 10-5 without worrying much as to what gas was left.

scholarly journals Research on detection method of leakage rate of rough pumping valve in space environment simulator

2020 ◽  
Vol 198 ◽  
pp. 03015
Author(s):  
Wu Yue ◽  
Guo Qingliang ◽  
Fang Mingyuan ◽  
Sun Juan ◽  
Guo Ziyin ◽  
...  
Keyword(s):  
Detection Method ◽  
High Vacuum ◽  
Leakage Rate ◽  
Space Environment ◽  
Vacuum System ◽  
Pumping System ◽  
Vacuum Degree ◽  
Valve Leakage

As an important part of the vacuum system in the space environment simulator, the rough pumping system reduces the vacuum degree of the container from atmospheric pressure to the pressure of the high vacuum system when the space environment simulator starts up. As the key equipment of the rough pumping system, the rough pumping valve plays the role of isolating the rough pumping system from the environmental simulator, and its leakage rate has a direct impact on the vacuum degree that the space environment simulator can reach. Therefore, it is very important to detect the leakage rate of the rough pumping valve. In this paper, the leakage rate detection method of the rough pumping valve is introduced, including the valve delivery stage and valve installation stage to the simulator stage, in order to provide some basis for the follow-up valve leakage rate detection work

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