PEEM is an electron microscope imaging technique. A surface is illuminated by ultraviolet (UV) radiation. The UV light generates photoelectrons for which intensity greatly depends on the chemical composition and the topography of the surface. The photoelectrons are accelerated into the microscope column, pass through a combination of magnifying lenses, and are projected onto a detector, converting the electron image into a visible image. The visible image displays the strongly magnified distribution of photoelectrons emitted from the surface.