An electron source possessing spatial and temporal coherence: A niobium nanoemitter

Here we present a reliable method for preparing a niobium nanoemitter, which is thermally and chemically stable. The tip apex is a (100) facet with a lateral dimension of ∼1 nm, surrounded by four (310) facets. This electron source will probably possess both spatial and temporal coherence if the emitter is cooled below the superconducting temperature of niobium.