| Abstract: | Field ionization and electron impact mass spectrometry complement each other well. Whereas bombardment of organic molecules with 70 eV electrons yields many characteristic fragment ions, which give valuable information about the structure of the molecules, the “soft” field ionization even of very unstable substances leads to the formation of relatively intense molecular ions which are often undetectable on ionization by electron bombardment. Field ionization also gives fragment ions that, though not very intense, are often very characteristic, and yield further information about the structure. The field desorption technique greatly reduces the degree of thermal decomposition of solid organic samples. New activation methods for field ion emitters lead to more intense ion beams and prolong the life of the emitters. Quantitative analyses using the field ionization mass spectrometer are of interest for hydrocarbon mixtures containing a very large number of components (e.g. several hundred). Simplified analyses are possible in particular for high-boiling petroleum fractions. |
