Tungsten has been condensed onto a clean tungsten point in a fieldhyphen;ion microscope held at liquidhyphen;nitrogen and liquidhyphen;hydrogen temperatures. Stepwise field evaporation has been employed to observe the structure of the deposit in atomic detail. The first layer of deposited tungsten atoms above the substrate appears to contain onehyphen;fourth to onehyphen;third vacancies. A brief discussion is given of the possibility of extending the range of specimens observable in the fieldhyphen;ion microscope by employing a shadowing technique which would leave a highly detailed imprint of the specimen on the emitter surface. It is concluded that the imperfect first layer of deposited tungsten observed in these studies would reduce the fidelity with which the details of the specimen could be observed for highhyphen;resolution microscopy.
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