Investigation of stability and charge state of Ne and Ar gas field ion source by time-of-flight mass spectrometry

Abstract

Charge state distribution of the working gases of the Ar and Ne gas field ion source (GFIS) were investigated by the time-of-flight mass spectrometry using a newly designed experimental system. GIFS emitters having few atoms on the top of the (111) surface of tungsten were formed by a remolding and field evaporation sequence with electrochemically etched h111i oriented tip. At a probe current of about 1 pA, the ratio of standard deviation of fluctuation and average ion current <2.5% was recorded from a single atom terminated emitter of the Ar GFIS. Mass analysis by the time-of-flight spectrometer showed that there were only singly charged ions both of the Ne and Ar GFIS. Furthermore, no impurity gas ion was detected in the mass spectrum.