Field emission microscope

Field emission microscopy (FEM) is an analytical technique used in materials science to investigate molecular surface structures and their electronic properties. Invented by Erwin Müller in 1936, the FEM was one of the first surface analysis instruments that approached near-atomic resolution.

FEM consists of a sharp needle emitter and a detector, such as a fluorescent screen. A negative electric field is applied to the emitter, emitting electrons from the surface. An image is formed at the detector due to the different current densities, which originates from the difference in electric fields and work functions on the emitter surface by the Fowler-Nordheim equation.