Mass Analyzers for FI and FD

In FI and FD, ions of 10-12 keV kinetic energy are generated as a continuous ion current. Conpared to El or Cl the ion current is weak and tends to fluctuate. The voltage drop across the whiskers (roughly proportional to the whisker length) causes an energy spread of the ions which results in poor resolution with single- 

Inghram, M.G. Applications of Field Ionization to Mass Spectrometry. J. Am. Chem. Soc. 1955, 77,500. Inghram, M.G. Gomer, R. Mass-Spectrometric Analysis of Ions from the Field Microscope. J. Chem. Phys. 1954, 22, 1279-1280. 

Beckey, H.D. Mass Spectrographic Investigations, Using a Field Emission Ion Source. Z. Naturforsch. 1959, 14A, 712-721. 

Beckey, H.D. Field-Ionization Mass Spectra of Organic Molecules. Normal Cl to Cg Paraffins. Z. Naturforsch. 1962, 17A, 1103-1111. 

---