Free Electron Attachment and Rydberg Electron Transfer to NF3 Molecules and Clusters

Free electron attachment in the energy range 0−10 eV and Rydberg electron transfer (RET) to NF3 molecules, NF3 clusters, and NF3/Ar clusters are studied by means of negative ion mass spectrometry. The experimental results are compared with density functional theory (DFT) calculations. In the free electron experiment gas-phase NF3 generates the dissociative attachment (DA) products F-, F2-, and NF2- appearing from a broad resonance around 2 eV, in agreement with an earlier beam experiment. The most abundant fragment, F-, exhibits a small “threshold” signal at incident energies close to 0 eV. This signal increases with the target gas temperature and is due to transitions from the neutral to the anion involving vibrationally excited states close to the intersection between the two potential energy surfaces. From the temperature dependence of this threshold signal the activation energy for the exothermic DA reaction e- + NF3 → F- + NF2 is derived as Ea = 0.1 ± 0.05 eV. Time-of-flight (TOF) analysis reveals th...