Materials Research Activities

Electron Microscopy Society of America meetings: 1968, 1975, and 1980

Three meetings of the Electron Microscopy Society of America (1968, 1975, and 1970)

by Tim Palucka

The Electron Microscopy Society of America (now known as the Microscopy Society of America) was founded in 1942, when it began holding annual meetings for instrument makers and users to gather and discuss the technology and its applications. The topics of papers given at these meetings present a snapshot of the state of electron microscopy at the time. A brief look at three of these meetings shows the evolution of the technology and its applications over a 12-year period.

In the brief twelve-year span of 1968 to 1980, the physical sciences overtook the biological sciences at EMSA meetings, judging solely on number of papers presented. A large part of this development is probably due to the emergence of the scanning electron microscope in 1965, which made examination of the surface of bulk specimens possible for the first time. Since physical scientists could now look at “real” samples instead of replicas or thin films, activity in microscopy of materials increased dramatically. With no similar dramatic development in biological microscopy, the balance shifted.

The willingness and ability of scientists to modify these expensive, complicated, instruments to meet their own needs is evident throughout this 12-year span. Indeed, many of the improvements in commercial instruments had their origins in the laboratories of the microscopists, not in the manufacturer's labs. This type of feedback from users had to be one of the major indicators to manufacturers as to what they should develop next. The incorporation of a large number of these improvements in sample stages and detectors led eventually to the commercial analytical and environmental microscopes of today.

Most important for our discussion is the fact that materials science as a discipline was recognized by electron microscopists after the emergence of the SEM.  While there was clearly a lag here—other histories place the emergence of the materials science at an earlier date—this is to be expected, because the microscopist could do very little with bulk materials until the SEM became available.  It might be said that the SEM helped to establish and solidify materials science as a field of its own.

1968: The 26th Meeting of the Electron Microscopy Society of America

In 1968, the 26th Annual meeting of EMSA was held in New Orleans, Louisiana, from September 16th through the 19th. 116 papers were presented dealing with biological applications of the electron microscope. Of the 27 papers devoted to topics that would fall under the heading of materials science (but, notably, were not grouped or named as such), 16 discussed lattice defects such as stacking faults or dislocations, 9 dealt with the effects of irradiation on materials, 1 examined fatigue crack nucleation, and 1 described surface treatment of materials. These materials topics were based almost exclusively on analysis of thin foils using the TEM. In addition, 5 papers discussed high voltage electron microscopy, 13 dealt with the relatively new SEM, and 6 dealt with electron diffraction applications, mainly selected area diffraction in the TEM.

A look at the titles of some of these papers is revealing:

  • N.C. MacDonald of the University of California, Berkeley, presented a paper entitled Computer-Controlled Scanning Electron Microscopy containing the following explanation: “A scanning electron microscope (SEM) has been connected to an IBM 1800 computer system. The computer not only processes the video information, but also generates the raster for the SEM.” So, at least as early as 1968 (if not before) computer's were being used to control and collect information from electron microscopes.
  • “Field Emission Cathode Electron Gun made of Tungsten” by A. N. Broers of the Thomas J. Watson Research Center. The title reveals that the field emission gun (FEG) that was to provide a brighter electron source for instruments in the 1970s was already being developed.
  • “High Resolution SEM using Lanthanum Hexaboride Cathode Electron Gun.” Again, the LAB6 electron source, which was to be an improvement over the original tungsten hairpin cathode, was being developed.
  • “A New Hot Stage for the Philips EM 200 and Its Calibration,” by J.W. Sprys and P.C.J. Gallagher of the Ford Motor Company Scientific Laboratory. The title demonstrates that microscopists were engaged in modifying their commercial instruments to fit their own needs, in this case the need to examine samples at elevated temperatures.
  • “A High Vacuum Electron Microscope,” D. N. Braski, Oakridge National Lab, Tennessee. Braski modified a Hitachi HU-11B electron microscope, giving it three ion pumps and two titanium sublimation pumps, which require no vacuum grease. Improvement in vacuum was a concern, and once again the researcher modified his instrument to attain it.
  • “A combined SEM/Electron Microprobe Analyzer,” V.G. Macres et al., Materials Analysis Company, Palo Alto, California. Materials Analysis Company Model 400S. “Designed to incorporate the most advanced features of a high performance electron microprobe analyzer with those of a medium resolution (1000 Ångstrom) SEM. Now that the SEM was established as a valuable tool, manufacturers such as the Materials Analysis Company were looking for ways to enhance its analytical power by adding existing detectors, like the electron microprobe.

These few examples show that most of the major inventions that would improve the electron microscope over the next 30 years –brighter electron sources, computer control, multi-detector systems, hot stages, and improved vacuum - were already being developed in 1968. The spirit of innovation that led researchers to modify complicated, expensive equipment for their own needs is also evident. In many cases, these homemade innovations made their way back to the manufacturer and eventually into commercial instruments.

1975: The 33rd Meeting of the Electron Microscopy Society of America. Las Vegas, Nevada.

While papers on biological applications still represented the majority of those presented at this meeting with a total of 210, the physical sciences (mainly materials science) were catching up with a total of 141 papers. Symposium titles included: applications of lattice imaging (5 papers); high resolution image formation and processing (4); phase transformation and identification (10); metals and alloys (10); ceramics, minerals, and textiles(12); thin films (12); instrumentation (26); defects (10); image and diffraction mechanisms (22); analytical techniques and processes (13) ; semiconductors (7); and precipitates and particulates (10). The concern with developing new instrumentation, and with learning to understand the mechanisms behind the images that came from these instruments, is evident in the high number of papers devoted to those topics.

A brief survey of papers:

  • “Digital Image Processing in High-Resolution Electron Microscopy,” by J. Frank of the Cavendish Laboratory in Cambridge, England. “An operation that produces an output image with a higher resolution than the input image may appear as witchcraft but is in fact feasible through clever use of a priori information, such as the knowledge of the object and noise statistics,” Frank wrote. He noted that high-resolution images generally contain a lot of noise from the substrate and the photographic grain. Using mathematical techniques to separate the noise from the signal results in higher resolution. Sometimes this requires additional microscopy, such as taking a micrograph of the substrate by itself in order to subtract out its noise contribution from the final substrate-plus-sample image.
  • “High Resolution Scanning Microscopy—What's Next?” by A.V. Crewe of the University of Chicago. Crewe maintained that there were two avenues toward the improvement of scanning microscopy: increasing the voltage of the instrument and correcting the spherical aberration of the electron lens system. His group was busy on both these projects, constructing a 1MeV scanning microscope with a theoretical resolution of less than 1 Ångstrom, and designing a spherical aberration corrector for a 100 kV instrument. Crewe also emphasized the need for improvement in the display systems (CRTs) for scanning microscopes, stating that the currently available 1,000 x 1,000 picture element resolution was “well below the amount of information which is available on the film in the conventional microscope, and much improvement is needed.”
  • “A 10,000 Lines/Field Scanning Electron Microscope System,” by G. Jones, H. Ahmed, and W. Nixon of the Engineering Department of Cambridge University. This paper may have provided some hope to Crewe in his request for a higher-resolution display.
  • “The Properties and Use of a Computer-Interfaced Video System for High Resolution Microscopy,” by W. Goldfarb and B. Siegel of Cornell University. The authors state that “A high resolution, low noise, slow scan video system directly interfaced to a minicomputer with disk and tape storage has been designed.” This approach combined an improved display system with computer control and data storage.
  • “Conversion of an EM-200 to a Dual-Gun Electron Microscope for TEM and SEM,” by A. Brewer, C. Gold, and P. Ong, details an attempt to make a combined instrument by mounting a second electron gun for SEM purposes below the viewing chamber.
  • An alternative approach toward the same end was presented by K. Anderson, K. Brookes, and J.M. Watson of AEI Scientific Apparatus Ltd. in “An SEM Attachment for the Corinth Electron Microscope.” This attempt involved a shared lens that acted as the final projector lens for the TEM as well as the objective lens for the SEM.

Other papers dealt with improving SEM sample mounts, vacuum chambers, specimen heating stages, and cryogenic specimen cooling stages.

1980: The 38th Meeting of the Electron Microscopy Society of America. San Francisco, California.

At this meeting 178 papers were presented in the physical sciences versus 166 for the biological sciences. The appearance of the words “materials science” appear in some of the titles of the papers given here; since this was not the case at the 1975 meeting, somewhere in the five-year span between these meetings it appears that materials science emerged as a field of its own in the minds of microscopists. Symposium titles included:

  • high voltage microscopy (10 papers)
  • image processing (8)
  • instrumentation (16)
  • analytical electron microscopy (21)
  • metals and alloys (12)
  • high resolution imaging (11)
  • micro-diffraction (4)
  • ceramics and catalysts (14)
  • detection systems (7)
  • polymers (6)
  • atmospheric pollutants (4)
  • focusing of charged particles (6)
  • microcharacterization of semiconductor materials (17)
  • alloys and phase transformations (12)
  • boundaries and interfaces (10)
  • iron and steel (11)
  • and thin films (9).

The 21 papers on analytical electron microscopy were given in three separate symposia dedicated to:

    1. applications
    2. core loss electron spectroscopy; and
    3. low energy losses, imaging, and x-ray spectroscopy.

The attempts to produce a combined SEM/TEM instrument detailed at the 1975 meeting had clearly come to fruition with the emphasis on AEM in 1980. The 17 papers on semiconductors show the emergence of this industry and the importance of electron microscopy in its development.

Papers of interest include:

  • “Applications of STEM to Problems in Materials Science,” by J. Vander Sande and A. Garret-Reed of the Massachusetts Institute of Technology. The authors stressed the high spatial resolution chemical analysis available using STEM, and the ability to obtain electron diffraction patterns from small volumes of material using micro-diffraction. They were also interested in image enhancement: “The serial data collection of the STEM permits easy interfacing to a computer for data storage and subsequent enhancement,” they wrote.  This was especially useful for contrast enhancement of polymer systems.
  • “Materials Science Applications of Analytical Electron Microscopy,” by W. Zaluzec.  The author was able to differentiate between phases of TiC and TiN precipitates in steels. “The potential uses of AEM in materials science is, at this time, seemingly endless,” he wrote.
  • “Applications of Electron Energy Loss Spectroscopy in Materials Science,” by O. Krivanek of the department of Materials Science and Engineering at the University of California, Berkeley. This paper detailed the chemical analysis of small (400 Ångstrom) particles at a weld in an iron-nickel alloy.
  • “Microprobe and Nonoprobe Analysis in TEM,” by M. Thompson of Philips in Eindhoven, The Netherlands. This paper described a nanoprobe capable of producing a beam as narrow as 4 nm in diameter for chemical analysis of small volumes of material.
  • “A Temperature-Controlled High Resolution Stage,” by M. Listvan, A. Crewe, and W. Mankawich of the University of Chicago. The authors developed a sample stage capable of maintaining temperatures in the range of +/- 100 degrees C for a 100 KeV STEM.
  • “Bringing the Real World Inside the High Voltage Microscope,” by E. Paul Butler of the Imperial College, London, describes dynamic, in-situ characterization of microstructural changes during phase transformations. This involved a controlled-temperature stage that could be adjusted during observation to promote phase changes.

This page was updated on 19 July 2002 by Arne Hessenbruch.