Performance and applications of the Toulouse 3 million volt electron microscope

Abstract

his paper describes the electron microscope and gives details of its performance at an operating voltage of 3 MV.Some initial results are reported concerning : penetrating power; resolving power; studies of radiation damage, and other interactions between electrons and crystalline materials. Several observations are also described concerning biological materials (bacteria, frog skeletal muscle, filaments from mushroom spores . . .).Because at high voltage, radiation damage is considerably reduced, the results obtained indicate a new range of applications of high voltage electron microscopy in biological ultrastructure research.

Current developments in high voltage electron microscopy

“…Dark-field images with good contrast even at 3 MV have been obtained of muscle (Fig. 5) by Dupouy (1973) and of ferritin by Massover (1974).…”

“…Accounts of other applications of the high voltage microscope in metallurgy and metal physics are given in the two sources already quoted (J. Microscopy, 97, parts 1 and 2, 1973;Swann et al, 1974), and also in Thomas (1972). The most important concern (a) dynamic studies of the movement of grain boundaries and dislocations, and the formation of cavities and precipitates, when a specimen is subjected to heating and/or straining in situ (Fig.…”

“…Applications in depth of the high voltage microscope to biological problems are still relatively few, as compared with its metallurgical uses. A detailed study of (Dupouy, 1973).…”

The High Voltage Electron Microscope in Biology

“…The maximum operating voltage of most HVEMs is I or 1.2 MV, but microscopes operating up to 3 MV have been constructed in Toulouse and in Osaka, and a l0 MV microscope is under construction in Japan. Full instrumental details of HVEMs are given in reviews by Cosslett (1969Cosslett ( , 1971, Dupouy (1968Dupouy ( , 1973Dupouy ( , 1974 and .…”

“…A regular geometric arrangement of these granules was very rare. Dupouy's (1968; dark-field imaging technique has also been used to obtain remarkable pictures of bacterial flagella (Dupouy et al, 1969) and of bacterial cell walls (Dupouy, 1973). The cell walls were lightly stained with phosphotungstic acid, and a regular periodic structure was visible ( Fig.…”