Instrumentation and Experimental Technique

Abstract

Electron microscope instrumentation is changing very rapidly, so this chapter outlines only the general features which are desirable in an electron microscope intended for microdiffraction work. Many of the instrumental requirements (particularly in the pole-piece region) will be found to be similar to those for energy-dispersive X-ray microanalysis. With the field-emission instruments used for the smallest probes, the need for a large tilting range may conflict with the electron-optical requirements for subnanometer probe formation, which requires a very small pole-piece gap. Several manufacturers are now prepared to offer the customer a series of compromise designs, from which a tilt range and minimum probe size combination can be selected. Certainly, for most of the applications described in this book which use the “incoherent” mode, a double tilt holder offering at least ±40° in one direction and ±60° in the other is desirable.