Electron Energy and Mass Spectrum

Electron Energy and Mass Spectrum

The figure shows a spectrum of ethylacetate (MW=88) for 70-eV electrons. Usually for GC/MS analysis, a 70eV electron is used for ionization. A reason to use this energy is that the mass spectra in many libraries, which are frequently used for identification of unknown sample peaks, are customarily measured with 70-eV electrons. When the electron energy is changed, the spectrum changes as per the following:

  1. Ion signal is most intense at around 70eV.
  2. When the energy is decreased, the spectrum will be less fragmented and the signal intensity seriously decreases. Ions cannot be produced below about 10eV.

CLICK"14eV" ("70eV")


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