Micron Probe Suppliers According to the b e s t information available, there are 8 companies e n g a g e d in d e v e l o p i n g or building x-ray micron probe instruments. T h e in formation set forth on the following p a g e s is b a s e d on data supplied b y the manufacturers. Prices range from $60,000 to $100,000. Manufacturers of the instruments are: Cameca Co.—France A p p l i e d Research Laboratories, Inc.—U. S. Philips Electronic Instruments—U. S. C a m b r i d g e Instruments Co., Ltd.—England H i t a c h i , Ltd.—Japan Efion Instruments, Inc.—U. S. Materials Analysis C o . — U . S. Associated Electrical Industries, Ltd.—England
The Microsonde. The Microsonde, built by the Cameca Co., a division of C.S.F., (France), is handled in the United States bv their exclusive licensee, International Electronics Corp. (INTEC) (1551 Franklin Ave., Mineola, Ν. Υ.) Design of the INTEC electron probe microanalyzer is based on the doctoral thesis work by Dr. M. R. Castaing of the University of Paris. Cameca has been producing this instru ment commercially for the past two years and has a dozen in use in France, Sweden, Belgium, England, and the U. S. The Microsonde has an electron beam which is electro statically corrected for astigmatism and which can be focused to a diameter of less than 1 micron. The beam is produced by an electron gun. The accelerating voltage is continuously variable in the range of 8 to 35 kv. By means of selector switching, the beam can be displaced electrostatically by in crements as small as 1 micron to allow accurate probing of an area of several square microns. Fluorescent materials are used to help adjust the beam. Two x-ray spectrographs are used to identify the elements. One uses a high output Geiger-Mueller detector connected directly to the Rochar electronic counter and integrating cir cuit. This is used for elements above atomic number 17. The other spectrograph carries a gas mixture flow proportional counter and preamplifier. By opening the 3 mm. beryllium window and operating this spectrograph in vacuum, elements down to sodium (atomic number 11) can be determined. A special preamplifier with pulse-shaping circuitry is used to amplify the feebler pulses from the proportional counter. Fast pumping equipment is used which evacuates to beyond 10~" mm. of mercury. The electromagnetic objective lens is so designed that the specimen is in a position of very low magnetic field. A one-inch sample holder is located in the center of a speci men holder providing for up to 40 pure elements or standard ized references. Samples up to 3 / 4 " X I / 2 " X 1 / 2 " can be examined. Central areas of still larger samples can also be analyzed. Specimen positioning is provided in three dimen sions. 30 A
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ANALYTICAL CHEMISTRY
An optical microscope with a long working distance reflect ing objective and illuminator are built into the second electro magnetic lens and can be adjusted easily so that the optical focus coincides with the electron probe focus. It has an 11X eyepiece and a magnification of 450X. Crystallographic studies of crystalline structure can be made using the excitation point as a source of x-rays such as in ob taining Kossel diagrams and in making diffraction studies. Photographic film and plate holders are supplied. EMX Electron Microprobe X-Ray Analyzer.
The new
EMX-electron microprobe x-ray analyzer, produced by the Applied Research Laboratories, Inc. (P.O. Box 1710, Glendale 5, Calif.) is now in production. In designing its microprobe instrument, ARL has centered much attention on the design of the final lens of the electron optical system. ARL says that in many respects the quality of this lens predetermines the performance capability of the instrument. This lens limits the minimum focal spot size which can be obtained with adequate current. Further, its size and shape limit the available space for the viewing system, the emergence angle of the x-rays, the smallest Bragg angles which can be obtained with a given focusing-type spectro meter, and in some cases, the maximum size which can be accommodated. ARL's objective lens features normal incidence of the elec tron beam or. the specimen and an emergence angle of 52.5 degrees. Thus high angle gives better performance, says ARL. The beam size can be varied from 0.5 micron to 300 microns at the surface of the specimen. The electron beam voltage ranges from I to 50 kv. in 500 volt steps. The lower limit of concentration is 0.02 to 0.1% for elements from 20 to 92. In some cases the range may be extended to
MICRON PROBES
FRACTION COLLECTORS . . . for every program
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Fractions in the turntable temperature-controlled. Fraction collectors removable for all-purpose cold-room work. • M o b i l e — o n casters.
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Four rows of 6 0 each.
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Time drop and volume collec tion.
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You can select exactly what you need from 1 2 different models! Immediate Delivery. · Prices from $ 4 0 0 . 0 0 F.O.B. N.Y.C.
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For complete description of all Fraction Collectors write for Bulletin
0.001%. Sensitivity for elements from atomic numbers 12 to 20 has not been determined but values should approach 0.1%. Since the electron objective lens in this instrument is in verted, the optical viewing system is simplified. The optical system has a 10X eyepiece, a magnification of 280X, and resolution of 1 micron. The exact spot being analyzed is under visual examination. The sample holder contains up to 8 specimens at one time and can be loaded rapidly. Maximum sample size is 1" di ameter by 3/16" thick. Simultaneous analyses of up to 3 elements is possible. The specimen stage provides translation in two mutually perpendicular directions both in the horizontal plane. Linear translation of 0.4" in two perpendicular directions allows coverage of the entire sample surface. Samples can be moved at a rate of 8 microns/minute. Three curved crystal spectrometers with receiver slits and detectors are available. These are all mounted within the high vacuum to reduce loss of radiation. Crystals used are lithium fluoride, quartz, sodium chloride, ammonium dihydrogen phosphate, and ethylene diamine D-tartrate. These cover the range of 0.36 A to 10 A. Automatic wave-length scanning speeds of 0.1 A or 0.02 A per minute are provided. Multitrons, sealed Geigers, and flow Geigers are used as de tectors.
3-4000
BUCHLER INSTRUMENTS, INC. formerly Laboratory Glass & Instrument Corp.
slNSTRIIMFNTl
5 1 4 W e s t 1 4 7 t h St., N e w Y o r k 3 1 , Ν . Υ .
Precision Instruments I
Telephone:
ADirondack
4-2626
Circle No. 110 on Readers' Service Card
H
1
C" Mevalonic Acîd-C14 DL-Tryptophan-2-C14
r
^
(ring labeled) 14
lndole-2-C Barbital-2-C14 FOR RESEARCH RADIOACTIVE Tracerlab CHEMICALS Shipment from stock
Jracerldb
World s Largest Radiochemical Laboratories
XKELEICET.J,
Circle No. 66 on Readers' Service Card
32 A
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ANALYTICAL CHEMISTRY
The vacuum system operates at 2 to 5 X 10~5 microns of mercury. It consists of a "roughing" pump and a diffusion pump plus an auxiliary mechanical pump to facilitate evacua tion of the sample chamber. Pump down time for the entire system is 1 hour and the sample airlock, 3 minutes or less. A standard ARL x-ray recording console is used as the readout device. The instantaneous integrated intensity of any one of the outputs of the three spectrometers can be measured and recorded continuously on a 10" recorder. An integrating circuit allows output of each detector to be read out sequentially on the pen recorder. This permits simultane ous reading of 3 elements. Norelco Electron Probe Microanalyzer. Philips Electronic Instruments (750 South Fulton Ave., Mount Vernon, Ν. Υ.) has two Norelco electron probe microanalyzers in use and two more ready for installation. The newest model (see photo) will be available in the latter part of 1960. The new model has two microscopes, one in the electron optical system and the other, a standard metallurgical micro scope, mounted so that the sample may be studied while still in the vacuum and out of the electron beam. A magnification of 350X is provided.
The new model will include a lens system that permits a beam size of 0.1 micron to 100 microns. A beam scanning device will be available to permit visual presentation on a cathode ray tube of element distribution in a 10 X 10 micron size area of the specimen. The beam can be positioned with out moving the sample. Electronics will include the latest type counter, rate meter, and pulse-height analyzer. The electron optical system consists of a biased gun and 2 magnetic lenses. Accelerating potential is adjustable from 1 kv. to 50 kv. in major steps of 5 kv. and fine control from 0 to 5 kv.
let JARRELL-ASH help you Modernize or Build your Chromatograph ! now
JARRELL-ASH offers CHROMATOGRAPH BUILDING BLOCKS
separately Like electron tubes,detectors are intricate devices. Buy them from specialists in design and construction. With the purchase of a single Jarrell-Ash detector oven body, your choice of detec tors is nowavailable. Thechromatographer can incorporate any one, or all, from the following family of Jarrell-Ash detectors — into his own system.
The system has a sensitivity of 0.1% for elements from number 20 up. Detection limits for elements below 20 have not been established. The specimen stage assembly is motor driven. I t will hold up to 4 samples or standards 1 / 2 " in diameter by 3 / g " thick. The specimen can be scanned linearly between 1 and 50 microns per minute. The vacuum system provides an operating pressure of ΙΟ -5 mm. of mercury or less. The fore-pump is followed by a diffusion pump. Pump-down time for changing samples is less than 10 minutes. The x-ray optics consists of three scanning type curved crystal spectrographs. Two of these are vacuum spectro graphs with a gas flow proportional counter for work with lower atom number elements. One is an air path scanning unit with a scintillation counter or sealed-off proportional counter. The crystals cover a range of 0.5 to 10 angstroms.
Cambridge X-Ray Microanalyser. The Cambridge Instru ment Co., Ltd. (13 Grosvenor PL, London, S.W.I., England) is in production on its scanning electron probe x-ray microanalyzer. More than 30 have been produced; one has been delivered and schedules call for several shipments this year including three to the U.S. Design of this instrument is based on one by D. A. Melford and associates at the Tube Invest ments Research Laboratory and in cooperation with V. E. Cosslett and P. Duncumb of the Cavendish Laboratory. Versatility is one of the principal advantages of this instru ment, claim the manufacturers. I t is possible, for example, to scan the sample and do point by point analyses and also scan slowly across a line. Two cathode ray tubes are used; one displays the electron image and the other the x-ray image. Facilities are provided
• Micro Diode Ionization (Lovelock) Micro Triode Ionization Cross Section Ionization Electron capture (affinity) experimental Flame Ionization
with the addition of a "NEW
JARRELL-ASH
"VARAVOLT"
Electrometer Power Supply The chromatographer can now modernize existingchromatographs, and build experi mental or special purpose units. For your "Building Blocks" in chromatog raphy instrumentation, look to Jarrell-Ash — detectors, amplifiers, ovens, injection systems, gas and liquid sampling valves, sample collectors, capillary and standard columns.
For complete literature write v_Ja.i~r-el I A s h
JARRELL-ASH
COMPANY
26 Farwell Street, Newtonville 60, Massachusetts COSTA MESA, CALIF. SAN MATEO, CALIF. LOMBARD (CHICAGO) ILL TORONTO, CANADA
ATLANTA, GEORGIA PITTSBURGH, PENN.
DEARBORN, MICHIGAN NEW BRUNSWICK, N. J. DALLAS, TEXAS ZURICH, SWITZERLAND
Circle No. 131 on Readers' Service Card
VOL. 32, NO. 9, AUGUST 1960 ·
33 A
M I C R O N PROBES
for superimposing the x-ray and electron images and for monitoring x-ray and electron intensities. This permits direct visual comparison between the surface topography of the specimen and the distribution of a selected element. The electron beam, accelerated in a range of 4 to 50 kv., is focused by means of magnetic lenses to a diameter of less than 1 micron. By means of scanning coils, the beam can scan up to y 2 sq. mm. Some of the electrons striking the surface are reflected with little loss of energy and others penetrate the surface and excite emission of x-rays. Resolution of the electron image is better than 1 micron and resolution of the x-ray image is approximately 1 micron. The range of elements is from atomic number 12 to 92. The rotatable specimen table holds one specimen and 13 pure metal standards. The usual range for specimens is 1/i" diameter up to 1 / g " long. Specimens and standards can be changed without destroying the vacuum. Larger samples can also be handled. The specimen may be rotated about the optical axis. An optical microscope with an 88X or 36X magnification is used to view the samples.
Standard Aerograph 110-C is complete with Brown 1 mv recorder. Price $1785.
What the
JL^^^,,
Can Do for You New columns and packings have greatly extended the usefulness of the Aerograph. It operates to 300° C with quantitative sample collection. Here are some of the many analyses the research chemist can perform with this economical instrument: FATTY ACID METHYL ESTERS-analyzed quantitatively in minutes. With new DEGS Column at 180°C methyl arachidonate is reached within 30 minutes. TALL OIL METHYL ESTERS-well resolved on 10 foot EGS at 200°C. Fatty acid and Resin acid methyl esters are quantitatively determined. FUSEL OILS—are ideally separated on a glycerol column. The amazing separation of active and isoamyl alcohol is easily accomplished. INSECTICIDES —rapidly analyzed in microgram quantities on silicone column at 250"C. PARAFFIN WAX —rapidly and quantitatively analyzed on silicone columns at 295°C. C-35 reached in 65 minutes. CITRUS OILS, MINT OILS-and other essential oils are efficiently separated on 20 foot Craig polyester column. CO, MIXED WITH OTHER GASES-C0 2 , 02, N2, CH„ CO are analyzed in less than 6 minutes. SUGARS —as methoxy methyl glycosides quantitatively determined with Craig polyester. Alpha and beta forms are easily separated. AMINES AND AMINO ALCOHOLS-aqueous amine solutions directly analyzed with minimum tailing with stationary phase on Fluoropak. Details on these and other analytical procedures appear in Aerograph Research Notes. Request your fre£ subscription and send us your sample for free analysis.
Wilkens
Dept. 0 / 6
INSTRUMENT & RESEARCH,INC.
P.O. Box 313 · Walnut Creek, Calif. · YEllowstone 5-1469 Circle No. 73 on Readers' Service Card
34 A
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ANALYTICAL CHEMISTRY
The vacuum system provides vacuum up to l(h 5 mm. of mercury. Pumping time is 8 minutes for the total column or 45 seconds after using the airlock for sample changes. A vacuum reservoir is available to back up the oil diffusion pump for periods up to 1 hour. The x-rays emerging through a port inclined at an angle of 20° to the surface of the specimen strike a curved analyzing crystal in the x-ray spectrometer. Crystals used are lithium fluoride for atomic numbers 20 to 92 and gypsum for atomic numbers 12 to 19. The crystals can be rotated relative to the incident x-ray beam and set to the correct Bragg angle for reflecting the characteristic emission of a chosen element through the window of a proportional counter. The signal from the counter is amplified and used to modulate the intensity of a beam scanning the long-persistence screen of one of two similar cathode ray tubes. The beam scanning the other cathode ray tube is modulated by an amplified signal from a photomultiplier. The beam of electrons scanning the samples and the beam scanning the cathode ray tubes are synchronized so that there is an exact correlation between the area scanned on the surface of the specimen and the x-ray and electron images. The electron image is similar to the optical image and the x-ray image shows the distribution and approximate concentration of a selected element. For quantitative analysis, the monochromatic x-ray signal is passed through a ratemeter and is recorded. Resulting curves are compared with those of pure samples.
Hitachi Electron Probe Microanalyzer. Hitachi, Ltd. of Tokyo, through its U. S. representative, Erb and Gray Scientific, Inc. (854 South Figueroa St., Los Angeles 17, Calif.) will be offering production models for sale in the U. S. early in 1961. The Hitachi Electron Microprobe Analyzer has a beam spot size of 0.1 micron. Its electron optical system has a lens system of a first and second condenser and projector and an accelerating voltage of zero to 50 kv. in seven steps. The specimen handling system consists of a chamber which permits moving the sample in an X-Y horizontal plane 2 x 1 mm. and vertically 0.5 mm. The scanning rate is 0.6 micron to 1 micron per second. Specimen size range is 1 to 10 mm. diameter. The visual observation system operates over a wave length of 0.6 to 8 angstroms. It will detect elements from atomic numbers 12 to 92 (magnesium to uranium). The crystal is curved (250 mm. radius) and consists of lithium fluoride or ammonium dihydrogen phosphate. The single spectrometer is of the focusing crystal type on a Rowland type circle. The detecting device consists of a scintillation counter, proportional counter, linear amplifier, and pulse height analyzer or ratemeter scaler. It has recording readout. The vacuum system consists of a dual rotary oil pump with automatic valving for airlocks, a diffusion oil pump, and an ionization type vacuum gage.
NYLAB presents...
THE BECKMAN DK SPECTROPHOTOMETER . . . . u s e d i n more a p p l i c a t i o n s t h a n all other recording spectrophotometers combined. The DK Spectrophotometer is automatic and simple to u s e . . . has excellent coverage of ultraviolet, visible and near infrared spectral regions . . . with wavelength range of 185 to 3500mu plus optional optics for probing the far-ultraviolet to 175mu . . . makes analyses faster, turns out more analyses using same number of laboratory p e r s o n n e l . . . lowest priced recording spectrophotometer available. The instrument also has a fluorescent screen for aligning the optics: Provision is made for recording diffraction patterns photographically. The Hitachi instrument with its power supply is 15 feet long, 5 feet wide, and 7 feet high. It operates on 115 v., a.c, and 3 kw. Elion DEM 301 Electron Microanalyzer. Elion Instruments, Inc. (430 Buckley St., Bristol, Pa.) is now in production of their Decimicron electron microanalyzer, model DEM 301. Three are scheduled for delivery during the first three months of 1961. Probe diameter of the DEM 301 is 0.1 micron. The mode of operation includes any and all of three analyses of exciting characteristic x-radiation, electron back-scattering analysis, and electron absorption analysis. In addition to point by point microanalysis, the instrument can produce x-ray images showing distribution of selected
You can arrange for a demonstration . . . more technical information . . . or for immediate delivery. Write or call today.
NYLAB New York Laboratory Supply Co., Inc. VAR.'CK
STREET
NEW
YORK
13, N.
Circle No. 69 on Readers' Service Card VOL. 32, NO. 9, AUGUST 1960
·
35 A
MICRON PROBES
Β LIC Κ MAN
FUME HOOD for safe handling of hazardous materials
elements over the area scanned. Areas up to 2 mm. may be scanned electronically. Fast or slow electronic viewing of specimen topography is possible. The instrument can analyze continuously or fixed position with its scanning goniometer and simultaneously for single elements with its three additional manually adjustable goni ometers for elements from atomic number 12 (magnesium) up. The main console contains the electron optical system, display tube-viewing systems with camera provision and specimen stage assembly holding three standard 1" metal lurgical specimens which can move in an X-Y horizontal plane. Oversize specimens can be handled.
Developed originally for handling bacteria and viruses, this all-stainless steel fume hood is equipped with a micro-biolog'ical filter canister incinerator. Polished, seamless, crevice-free construction with rounded corners makes cleaning" and decontamina tion easy and sure. Many convenience features; units 4, 5, 6 or 8 feet long, with or without stand or filter canister. Write for illustrated folder describing 22 different kinds of enclosures for safe handling of hazardous materials. S. Blickman, Inc., 9608 Gregory Avenue, Weehawken, New Jersey.
BLICKMAN SAFETY E N C L O S U R E S Look for this symbol of quality
Circle No. 27 on Readers' Service Card
spectroscopists: infrared reference spectra of commercial products available in convenient groups Each group of spectra listed here contains w h a t Sadtler Research Laboratories has found to be most useful to the spectroscopist. For spectra groups other than those listed, please consult the laboratory.
401 404 407 410 414 417 420 425 430 435 440 448 455 460 465
AGRICULTURAL CHEMICALS FIBERS PERFUMES A N D FLAVORS PIGMENTS A N D DYES PLASTICIZERS POLYMERS POLYOLS ROSINS RUBBERS SOAPS, FATTY OILS SOLVENTS SURFACE ACTIVE AGENTS TEXTILE CHEMICALS WAXES PETROLEUM CHEMICALS
CHEMICAL
THE
QUAN.
DESCRIPTION
GROUP NO.
CONSULTANTS
SADTLER FIFTEEN SEVENTEEN VINE
65 51 50 60 500 605 54 80 100 64 700 860 80 100 64
SINCE 1874
RESEARCH LABORATORIES STREET
·
PHILADELPHIA
2,
Circle No. 85 on Readers' Service Card 36 A
·
PRICE $ 32.50 25.50 25.00 30.00 250.00 302.50 27.00 40.00 50.00 32.00 350.00 430.00 40.00 50.00 32.00
ANALYTICAL CHEMISTRY
PENNSYLVANIA
This console also contains x-ray optics including a high take-off angle, three fixed-curve crystal spectrographs, and a scanning goniometer spectrograph, detectors, preamplifiers, d.c. high voltage supplies, and regulating circuitry for multiple d.c. high voltage supplies separately regulated for four detect ing channels. Provision is made for scintillation-, proportional-, flow counters, and Geiger counters as desired, high voltage trans former, and regulated power supplies permitting adjustment through the 2 kv. to 50 kv. range. The main console section also includes a rapid vacuum pumping system, reservoir, and path system (which permits sample changing without breaking the vacuum), lens current stabilizers, high voltage stabilizers, operating and analyzing controls, and meters. The electron panel section contains the regulated power supplies, four independent radiation detecting channels with amplifiers, pulse height analyzer, ratemeter, and recording system. The high speed channel has a resolution of 1 micro second. Preset count and preset time are included. The instrument is adaptable for Kossel patterns for meas urement of lattice parameters and for projection micro radiography. The MAC Microprobe. The electron microprobe analyzer made by the Materials Analysis Co. (3385 Louis Rd., Palo Alto, Calif.) is called the "MAC Microprobe." A company spokesman states that their probe is in the prototype stage of development with the exception of the x-ray spectrograph system which is still undergoing some design modifications. Production of two units has already been started. They should be completed by the end of the year. The MAC Microprobe features an electron microprobe as small as one micron in diameter. Designers of this instrument emphasize the importance of simultaneous observation of the specimen during electron bombardment and use a refracting type optical microscope and illuminator for this purpose.
MICRON PROBES This has magnification of 240X and 600X. The microscope is titled 30° to the electron optical axis to eliminate interference with the electron beam. The specimen surface and plane of the specimen translational motions are also inclined 30° to the horizontal plane. The tilt reduces the sensitivity to sur face roughness of the analyzed x-ray beam. Fluorescent mate rial is used to assist in focusing the electron beam.
uranium (92) is analyzed by means of a spectrometer with a bent crystal (LiF or quartz), and Geiger Mueller counter tube and recorder. Elements from aluminum and magnesium are analyzed with the aid of a proportional counter, amplifier, and pulse height analyzer. Mica or gypsum crystals can be used to analyze lighter elements although this leads to a loss of intensity.
Electron Gun
Auxiliary Lens
Aperture Diaphragm Light Optical Axis Astigmatism Compensator Objective Lens
X-Radiation
Specimen
Electrons from the electron beam are accelerated by a high voltage variable from 10 to 40 kv. The electron beam is focused by an auxiliary magnetic lens and an objective mag netic lens. Specimens may be moved one inch in each of two perpen dicular directions as well as 1 / 4 " vertically. Up to 6 standard metallographic specimens or standards can be accommodated. Samples can be scanned automatically at the rate of 10 microns per second. The x-ray analysis system consists of two fixed curved crystal spectrographs capable of analyzing elements of atomic numbers 12 to 92. The x-ray detecting instrumentation con sists of a stabilized counter high voltage supply, two GeigerMueller counters, a flow proportional counter, two ratemeters, linear amplifier, pulse height analyzer, and two chart record ing potentiometers. An oil diffusion pump and mechanical forepump provide operating pressures of less than 10 -4 mm. of mercury. In addition to chemical analyses, the instrument can also be used to analyze crystal orientation by recording Kossel lines on a photographic film. Other applications include scanning x-ray microscopy and scanning electron microscopy. X-Ray Microanalyzer. The x-ray microanalyzer being pro duced by Associated Electrical Industries, Ltd., (ΑΕΙ) is based on the technique developed initially by Castaing in France. The ΑΕΙ instrument with a probe diameter of 1/i micron, is used to probe an area one micron in diameter. The x-radiation developed from elements ranging from chlorine (17) to 38 A
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ANALYTICAL CHEMISTRY
The ΑΕΙ instrument consists of three main units: the desk cubicle with the electron probe stack, spectrometer, optical microscope, and vacuum equipment to evacuate the probe stack and spectrometer; the rotary pump is separated to prevent vibrations; the 1-50 kv. voltage supply and electron lens supply are housed in a cabinet ; the recording and other equip ment are housed in a separate cubicle. A metallurgical microscope provides a range of magnifica tion from 100X to 400X. The specimen chamber, situated between the optical micro scope and the probe stack, holds up to 6 specimens on a rotatable drum inclined at 30° to the vertical to facilitate entry of x-rays into the spectrometer. Two magnetic lenses are used to focus the electron beam. Accelerating voltage of the gun ranges from 10 to 50 kv. The lens can be adjusted to provide small shifts of the electron beam thus providing a scanning system. The recording equipment consists of a combined scaler and ratementer. Mechanical scanning of the specimen is pos sible using a recorder strip chart. This gives a continuous record of the distribution of a particular element in the specimen. The rotary pump with its two separate single-stage pumps and the two oil diffusion pumps attain ultimate pressures of 10—β mm. of mercury. The ΑΕΙ instrument will handle samples as large as a 1 /'2" cube. Areas of the samples ranging between 10 X 10 microns to 100 X 100 microns may be scanned. Slow scanning of the electron probe along a line on the stationary specimen can be done. The electron and x-ray pictures of any given area can be displayed simultaneously on two cathode ray tubes. Either picture can be photographed on 35 mm. roll film. A third cathode ray tube may be used to monitor electron line intensity to facilitate focusing, to display pulse height distribution, or to monitor output of power supplies.
