BRIGHTNESS MEASUREMENTS OF NANOMETER-SIZED FIELD-EMISSION-ELECTRON SOURCES

The brightness of nanometer-sized field-emission-electron sources have been measured experimentally. Ultrasharp tungsten (111) single-crysta l tips were fabricated in situ using Ne sputtering and field evaporati on, and monitored using field ion microscopy. The average brightness o f single-atom-terminated nanotips was found to be 3.3 X 10(8) A cm-2 s r-1 at 470 V, or 7.7 X 10(10) A cm-2 sr-1 when extrapolated to 100 kV. These results show an improvement of about two orders of magnitude in source brightness over existing cold field-emission-electron sources, and produce a beam with greater particle flux per unit energy than th ose obtainable using current synchrotron/wiggler/undulator devices.