The brightness of nanometerhyphen;sized fieldhyphen;emissionhyphen;electron sources have been measured experimentally. Ultrasharp tungsten (111) singlehyphen;crystal tips were fabricatedinsituusing Ne sputtering and field evaporation, and monitored using field ion microscopy. The average brightness of singlehyphen;atomhyphen;terminated nanotips was found to be 3.3times;108Athinsp;cmminus;2thinsp;srminus;1at 470 V, or 7.7times;1010Athinsp;cmminus;2srminus;1when extrapolated to 100 kV. These results show an improvement of about two orders of magnitude in source brightness over existing cold fieldhyphen;emissionhyphen;electron sources, and produce a beam with greater particle flux per unit energy than those obtainable using current synchrotron/wiggler/undulator devices.
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