Dissociative electron impact ionization of methyl tert-butyl ether: total ionization cross-section and kinetic energy distributions

Kinetic energy distributions and yields of the ions produced in the electron impact ionization of methyl tert-butyl ether (MTBE) have been measured by TOF mass spectrometry. The detection efficiency as a function of the initial ion kinetic energy has been carefully evaluated by means of a Montecarlo simulation of the experimental conditions. The resulting kinetic energy spectra show that almost all the heaviest ions are produced with quasi-thermal energy distribution, while the smaller fragment ions H+ and CH 3 + exhibit in addition substantial non-thermal components. As a final result, the total ionization cross-section of MTBE in the range 20–150 eV of the ionizing-electron energy has been derived and calibrated against the argon, chosen as a reference gas.