Analytical electron microscope development

Historically, EELS is one of the oldest spectroscopic techniques based ancillary to the transmission electron microscope. In the early 1940s the principle of atomic level excitation for light element detection capability was demonstrated by using EELS to measure C, N, and O. Unfortunately, at that time the instruments were limited by detection capabilities (film) and extremely poor vacuum levels, which caused severe contamination of the specimens. Twenty-five years later the experimental technique was revived with the advent of modern instrumentation. The basis for quantification and its development as an analytical tool followed in the mid 1970s. Recent reviews can be found in the works by Joy, Maher and Silcox " Colliex and the excellent books by Raether and Egerton. ... 

The electron microscope offers a unique approach for measuring individual nano-sized volumes which may be catalytically active as opposed to the averaging method employed by spectroscopic techniques. It is just this ability of being able to observe and measure directly small crystallites or nano-volumes of a catalyst support that sets the microscope apart from other analyses. There have been many studies reported in the literature over the past fifteen years which emphasize the use of analytical and transmission electron microscopy in the characterization of catalysts. Reviews (1-5) of these studies emphasize the relationship between the structure of the site and catalytic activity and selectivity. Most commercial catalysts do not readily permit such clear distinction of physical properties with performance. The importance of establishing the proximity of elements, elemental distribution and component particle size is often overlooked as vital information in the design and evaluation of catalysts. For example, this interactive approach was successfully used in the development of a Fischer-Tropsch catalyst (6). Although some measurements on commercial catalysts can be made routinely with a STEM, there are complex catalysts which require... 

The innovator must be supported to the maximum extent possible by staff and facilities. By this, I don t mean that he/she needs six assistants when one or two are enough, and the latest model electron microscope is usually not required when the model purchased five years ago has been updated with necessary auxilary equipment. But it is certainly counterproductive to understaff the innovator s work and unconsciously force him/her to apply his/her talent to devising supportive measures that are more readily supplied by an (or another) assistant. Supportive equipment, since it often involves significant capital outlay, is another matter but I suggest that it is prudent to provide the best equipment the company can afford to provide maximum information and shortest possible response time in supportive functions like analytical or instrument service. After all, time is nearly always the most vital commodity in any research or development project - earlier completion means a plant on stream... 

Owing to the rapid advances in computing power, SEM has become relatively easy. This enables development of microscopes to be focused on the analytical aspect of the problem. As a consequence, the latest generation of these instruments is increasingly being used for process and product control. This shift in the application of electron microscopes started in the semiconductor industry, where SEM is... 

The classical polarizing light microscope as developed 150 years ago is still the most versatile, least expensive analytical instrument in the hands of an experienced microscopist. Its limitations in terms of resolving power, depth of field, and contrast have been reduced in the last decade, in which we have witnessed a revolution in its evolution. Video microscopy has increased contrast electronically, and thereby revealed structures never before seen. With computer enhancement, unheard of resolutions are possible. There are daily developments in the X-ray, holographic, acoustic, confocal laser scanning, and scanning tunneling micro-... 

Improvements in the resolution and versatility of microscopic techniques have come about rapidly. TEM, STEM, and high-resolution electron microscopy have helped the catalytic chemist to analyze the effects of metal-support interactions and particle-size effects—developments that will probably lead to improvements in commercial technologies. Several novel analytical methods, arising from very clever experimentation, were discussed at the... 

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