If you have been hibernating for several weeks you may have missed the headlines and magazine covers exclaiming about “Life on Mars!” The basis for all of this excitement is an article in Science by Dr. David S. McKay of the Lyndon B. Johnson Space Center in Houston and eight of his colleagues from several academic institutions. The reader of this column will not be surprised by the fact that microscopes were used to detect evidence of life on a meteorite from Mars.

The first consideration was whether or not the meteorite was in fact a fragment of the martian surface. The specimen, known as ALH84001, is from a class of meteorites that appear to have resulted from impacts on Mars, some of the specimens landing in Antarctica where this one was recovered. Trapped gases (in glass droplets and stringers) in several of the family of meteorites closely match the martian atmosphere for several gases over 8 orders of magnitude range in abundance. Whereas ALHB4001 did not contain such trapped atmospheric gases, its elemental and isotopic composition closely resemble the meteorites that do.

The recent note by J.D. Watson in Science (1993) is another of the periodical advice columns in which someone of renown gives his or her perspective of how to succeed in this most difficult of fields. And a very good article it is. I find no fault with any of the four rules presented which I quote as follows: 1) “To succeed in science you have to avoid dumb people.” 2) “To make a huge success, a scientist has to be prepared to get into deep trouble.” 3) “Be sure you always have someone up your sleeve who will save you when you find yourself in deep s—.” 4) “Never do anything that bores you.” Unfortunately, these four rules are directed to a level of scientist that clearly bypasses most of us irrespective of how many good intentions we may have. Therefore I feel obliged to submit a revised list of thoughts for us average beings who plow through the days in an average research environment.

In order to perform quantitative X-ray microanalysis many parameters, representing the various stages of X-ray generation and transport through the specimen at the chosen experimental conditions, must be known for all of the elements that might be encountered. Although ideally quantification is done by reference to standards so that only the functional variation of these parameters is required, in current practice it is increasingly necessary to work in situations where standardization is impossible and consequently where absolute magnitudes must be known. The quality and quantity of data that is now available varies widely.

An innovative technique has been developed which allows simultaneous cleaning of a sample and a specimen stage which minimizes and, in some cases eliminates, contamination of inorganic specimens analyzed via SEM.TEM, STEM and AEM.

The technology involves subjecting the specimen and the specimen stage to a reactive plasma gas which efficiently removes a wide range of contaminants from critical surfaces. The procedure may be carried out prior to inserting the specimen and specimen stage into the EM via an externally produced accessory unit and can be extended for use on all types of electron microscopes where the sample and stage are loaded external to the instrument. Such an instrument was produced and implemented first by Dr. Nestor Zaluzec at Argonne National Laboratory. His system modified a commercially available pfasma etching system which included adapting it to accept a side entry holder.

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at IMIST. The fundamentals and results are discussed in this paper.