Influence of the cross-section of gas molecules upon detection on the environmental SEM

Environmental scanning electron microscopy exploits presence of gas or water vapour in the specimen chamber. Molecules of the gaseous environment can be ionised by electrons, which can compensate the surface charge on thespecimen (at the pressure approx. 200 Pa). At higher pressure of gases and water vapour in the specimen chamber (more than 609 Pa) specimens with content of water can be observed