The samples largely have to be viewed in vacuum, as the molecules that make up air would scatter the electrons. An exception is liquid-phase electron microscopy using either a closed liquid cell or an environmental chamber, for example, in the environmental scanning electron microscope, which allows hydrated samples to be viewed in a low-pressure (up to ) wet environment. Various techniques for in situ electron microscopy of gaseous samples have been developed.
The samples largely have to be viewed in vacuum as the molecules that make up air would scatter the electrons An exception is liquid-phase electron microscopy using either a closed liquid cell or an environmental chamber for example in the environmental scanning electron microscope which allows hydrated samples to be viewed in a low-pressure (up to ) wet environment Various techniques for in situ electron microscopy of gaseous samples have been developed