Field Ion Microscope Combined with a Quadrupole Mass Analyzer and an Energy Analyzer

Abstract

A field ion microscope is combined with a quadrupole mass analyzer for chemical identification of field ionized or desorbed ion species and with a retarding grid energy analyzer for determining the distance of ionization of these species relative to the surface atoms. With its present sensitivity this instrument is capable of detecting the image gas ions down to a partial pressure of 3×10−7 Torr at 78 K by scanning the mass range of 10 amu corresponding to 2 ions/sec/amu to the detector. The preliminary experimental results for field ionization of hydrogen on iridium (001) are discussed.