Electron ionization of NF3

Experimental and theoretical study on electron ionization of NF3 is carried out in terms of the absolute partial and total ionization cross sections. The measurements are done in crossed electron beam-molecular beam geometry for electron incident energies ranging from 0 to 500 eV using a newly built time of flight mass spectrometer with emphasis on complete collection, transmission and detection without mass and energy discrimination, while maintaining reasonable mass resolution. The cross sections are put on the absolute scale using the relative flow technique. The partial cross sections and the thresholds for the formation of NF3+, NF2+, NF+, F+, and N+ are compared with the previous results. Our cross section values for lower mass ions N+, F+, NF+ are found to be considerably higher as compared to previous measurements. We also have calculated the total scattering and total ionization cross sections using the spherical complex optical potential (SCOP) formalism and compared with existing data. While the total scattering calculations agree with the existing experimental results, the total ionization cross sections do not agree well with our experimental data. The present experimental results agree with those estimated using “Deutsch–Mark formulation with new additivity rules”, which were not in agreement with the existing experimental results for the case of NF3.

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► Partial and total electron impact ionization cross sections for NF3 are measured.
► Total scattering and total ionization cross sections are also calculated.
► Measurements differ considerably from previous measurements and present calculations.
► The measured cross sections agree well with the “new” Deutsch–Mark additivity rule.
► The appearance potentials for various ions are measured, estimated and compared.