Nanosecond double-frame electron microscopy of fast phase transitions

Abstract

A high-velocity technique, capable of producing for the first time multi-frame short exposure time images in the electron microscope, is introduced. It is based on an electron image detector, consisting of a successively pulsed multichannel plate, acting as a fast shutter and a high-gain image amplifier, followed by a scintillator on positive potential as image converter. A frame-shifting plate capacitor, installed above the projector lens, places the succeeding images on unexposed areas of the multichannel plate, thus avoiding the long recovery time (milliseconds) of fired areas. Exposure times of 10-50 ns and delays >or approximately=100 ns between the shots are realised. Successive stages of laser pulse-induced crystallisation and evaporation of amorphous films are visualised with this new method.