Environmental scanning electron microscopy for the study of ‘wet’ systems

Environmental scanning electron microscopy (ESEM) is a comparatively new version of electron microscopy that has yet to be fully exploited in the field of colloid science. It has the key advantage over conventional scanning electron microscopy that wet samples can be looked at in their natural state with essentially no prior specimen preparation. This can be achieved because water vapour can be maintained in the specimen chamber. Dynamic experiments can also be carried out by controlling the local vapour pressure, so that hydration or dehydration can take place in situ and in principle (beam damage permitting) whilst imaging. Despite these attractive features, the potential of ESEM appears not yet to have been fully appreciated for the study of colloids.