Absolute cross sections for the electron impact ionization of the NF ₂ and NF free radicals

We report measurements of the absolute cross sections for the electron-impact ionization of the NF₂ and NF free radicals from threshold to 200 eV. At 70 eV, the absolute parent NF₂ and NF ionization cross section are 1.25±0.23 Ų and 1.05±0.19 Ų, respectively. We found little evidence of the presence of vibrationally excited radicals in the incident target beam for both NF₂ and NF. We also studied the dissociative ionization of NF₂ and NF. The absolute cross section for the formation of the NF⁺ fragment ions from NF₂ was found to be 0.75±0.15 Ų at 70 eV. The NF⁺ fragment ions are formed with little excess kinetic energy. The only significant pathway leading to the observed NF⁺ fragment ions is the single positive ion formation. Our data show no indication of the presence of double positive ion formation channels or positive-negative ion pair formation processes. Cross sections for the formation of the atomic fragment ions F⁺ and N ⁺ from both NF₂ as well as NF were found to be small with maximum values of less than 0.1 Ų at 70 eV in all cases.