It is impressive enough that individual atoms can be resolved with the atomic force microscope (AFM), but who would have thought that atomic motion would be detected so soon? Atomic resolution with the AFM was only recently achieved. As reported in this column, Franz Giessibl was able to demonstrate local resolution of adatoms of the Si(111) 7×7 reconstructed surface. Now, Yasuhiro Sugawara. Masahiro Ohta, Hitoshi Ueyama, and Seizo Morita of Hiroshima University have demonstrated atomic resolution of the surface of InP(110). Not only that, but images taken about one minute apart show that some of the atoms had moved! Sugawara et al, used a very compact AFM under ultrahigh vacuum (4 X 10-8 Pa) to accomplish this impressive feat. A stiff (spring constant of 34 N/m) silicon cantilever was used. This stiffness, along with a mechanical resonant frequency of 151 kHz, was used to keep the cantilever from jumping onto the sample and crushing the initially sharp tip.

In the November issue of this publication, we described how focused ion beam (FIB) microsurgery is used to successfully cross-section and prepare material-specific samples for SEM and TEM analysis. Material specific samples have two or more components possessing different characteristics, such as hardness and chemical etch or sputtering rates. Traditional sample preparation techniques (mechanical grinding and polishing, broad ion beam etching, and chemical etching) alter, delaminate, or destroy these samples.

FIB handles the preparation of these difficult samples well because of its milling geometry and the high current density of the small beam.

Did I ever tell you about my first optical enginsering project? It was a video projector which used many innovative ideas, including one of the first liquid crystal video displays. It was dssigned to be the brightest projector ever made and was used in a helmet mounted display prototype. My first job out of college was to gather the parts, put it together, and measure its characteristics. To make a long story short, I had to turn the room lights out to see the image! What made a 20,000-footlambert design into a 20- footlambert display? Illumination! I learned a lot about illumination in those few short weeks, and everything I learned is directly applicable to microscopes. In fact the whole science of illumination was developed by microscapists. Electron microscopes deal with exactly the same concepts.

The ability of scanning beam x-ray microanaiysis to show the spatial distribution of elements was recognized quite early. At first it was done one element at a time by wavelength dispersive spectroscopy (WDS), but when energy dispersive spectroscopy was developed, that became the technique of choice. Because there have been several significant improvements in the technology, and also because maps are used so universally, I thought a review of the technology from the early days to the latest technology might be interesting. Though modern maps are ail digital, the original analog “dot” maps are used by a few even to this day. Other names for the technique are sometimes used such as “x-ray image”, which is correct but can be confused with radiography. Compositional image has also been used, but the term is broad and includes more than x-ray maps. Consequently, the universally recognized term “maps” will be used.

Al Soeldner's article in the November issue of this publication entitled “Staying Alive” contains a lot of good, solid advice that all of us who operate service laboratories should take to heart. Whether our laboratories are public or private, his advice on sticking to what we know how to do, understanding how to put the client first in the “service” environment and establish a “user friendly” climate is sound and should be clearly heard by all.

There is, however, one point on which I do not agree with Al, and that is the scope of work which is appropriate for various laboratories. While he does discuss the possible problem of “agency policy” which may conflict with offering services to a broader user base, he might not emphasis that the problem created by the agency policy (if it exists) is probably based on a solid understanding of the legal climate in which we all operate.

On the eighth day, chemical analysis began. Adam, recovering after cooperating with God in creating Eve, felt the first pangs of hunger. Looking around, he spied a pile of stones left over after creation of some nearby mountains. He rejected a soft friable sandstone and chose a hard granite rock, took careful aim at a rabbit, and hit it squarely between the eyes. This was the basis for the first real meal in the Garden of Eden. A day or two later, Eue took a whiff of the rabbit carcass, thought for a moment, then fed it to the dog.

Thus, the first chemical analytical instruments were Adam's eye and hand and Eve's nose. These, plus taste, sufficed by themselves for a long time thereafter but, eventually, refinements were necessary.

The world of electron microscopy is in a period of transition from acquiring images on film to acquiring images digitally, using CCD cameras, for example. It would be useful to know how much information there is on a piece of film, in order to know how film compares with digital methods and to be able to make good judgements on the optimum moment to change from one technology to the other.

This is an attempt to use simple arguments to estimate just how much information there is in an image exposed on film in the transmission electron microscope. The main reason for addressing this issue is that, while many people are affected by it, there seems to be little agreement on the answer.

A.C. magnetic fields exist throughout every EM site. For a given site, then, how does one predict when EM interference problems are likely to occur? Obviously, an accurate, meaningful magnetic field survey is the first step toward evaluating site EM magnetic field compatibility. Consequently, this article in our series will describe measurement equipment and techniques for achieving accurate, unambiguous magnetic field characterization.

In a previous article (Part II: “ACMF/EM Antipathy”, Microscopy Today, November ‘95), we examined several types of sources which produce alternating current magnetic fields (ACMFs). In near proximity, or at sufficiently high power levels, any of these sources (e.g., transformers, power cabling, ground currents, and/or combinations thereof) can affect EM operation. In this article, we will review specific instrumentation and methods for accurate magnetic field survey data collection and interpretation, a necessary prior step for EM interference prediction and resolution.

Despite the potential of the technique, electron tomography has yet to be widely used by biologists. This is in part related to the rather daunting list of equipment and expertise that are required. Thanks to continuing advances in theory and instrumentation, tomography is now more feasible for the non-specialist. One barrier that has essentially disappeared is the expense of computational resources. In view of this progress, it is time to give more attention to practical issues that need to be considered when embarking on a tomographic project. The following recommendations and comments are derived from experience gained during two long-term collaborative projects.