Investigation of charge state of field-ionized noble gases by time-of-flight mass spectrometry

Abstract

Charge state distributions of Ar and Ne Gas Field Ion Source (GFIS) were investigated by time-of-flight mass spectrometry using a newly designed experimental system. GIFS emitter having few atoms on the top of a (111) surface of tungsten were formed by remolding and field evaporation sequence with electrochemically etched oriented tip. At the probe current of about lpA, the ratio of standard deviation of fluctuation and average ion current < 2.5% was recorded from a single atom terminated emitter Ar-GFIS. Mass analysis by time-of-flight spectrometer showed that there were only singly charged ions both of Ne- and Ar-GFIS. Furthermore, no impurity gas was detected in the mass spectrum. These findings look promising for the development of both Ne and Ar GFIS systems.