Fragmentation of the valence electronic states of NF3+ studied by threshold photoelectron–photoion coincidence spectroscopy

Dominic Seccombe, Gary Jarvis, B. O. Fisher, Richard Tuckett

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


The valence threshold photoelectron spectrum of NF3 is reported for the first time in the literature, and threshold photoelectron–photoion coincidence (TPEPICO) spectroscopy has measured, state-selectively, the decay dynamics of the valence states of NF3+ in the range 13–23 eV. Vacuum–UV radiation from the Daresbury synchrotron source dispersed by a 1 m Seya-Namioka monochromator photoionises the parent molecules. Electrons and ions are detected by threshold electron analysis and time-of-flight mass spectrometry, respectively. TPEPICO spectra are recorded continuously as a function of photon energy, allowing coincidence ion yields of the fragment ions and the breakdown diagram to be obtained. A comparison of the integrated threshold photoelectron and the total ion signals as a function of energy suggests that, in the range 16–19 eV, autoionisation via Rydberg states of NF3makes a significant contribution to the production of threshold electrons. The 50% crossover energy for production of NF2+ from NF3+ is determined to be 14.10±0.05 eV. The first onsets for NF2+ and NF+ production are 13.95±0.05 and 17.6±0.1 eV, respectively. The majority of the Franck–Condon region of the X̃2A1 ground state of NF3+ is stable with respect to dissociation to NF2+, whereas the unresolved Ã2E/B̃2A2 states and most of the C̃2E state dissociate exclusively to NF2+. The D̃2A1 and Ẽ2E states dissociate to NF+. Translational kinetic energy releases have been measured in NF2+ and NF+ at the energies of the Franck–Condon maxima of the valence states of NF3+. The results are compared with models assuming statistical and impulsive dissociation. The Ã/B̃ states of NF3+ dissociate directly from the excited-state potential energy surface to NF2+, whereas the higher-lying C̃ state probably dissociates off the ground-state surface following rapid internal conversion. It is not possible to correlate unambiguously the formation of NF+ with either F2 or 2F, although on energetic grounds the latter products are more likely. Assuming that the neutral products are 2F, no information is obtained whether the two N–F bonds break simultaneously or sequentially.
Original languageEnglish
Pages (from-to)335-346
Number of pages12
JournalChemical Physics
Issue number3
Publication statusPublished - 15 Dec 1999


Dive into the research topics of 'Fragmentation of the valence electronic states of NF3+ studied by threshold photoelectron–photoion coincidence spectroscopy'. Together they form a unique fingerprint.

Cite this