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Negative‐ion/positive‐ion coincidence spectroscopy as a tool to identify anionic fragments: The case of core‐excited CHF3

Research output: Contribution to journalArticleScientificpeer-review


Original languageEnglish
Publication statusAccepted/In press - 11 Dec 2019
Publication typeA1 Journal article-refereed


We have studied the dissociation of the trifluoromethane molecule, CHF3, into negative ionic fragments at the C 1s and F 1s edges. The measurements were performed by detecting coincidences between negative and positive ions. We observed five different negative ions: F‐, H‐, C‐, CF‐, and F2‐. Their production was confirmed by the analysis of triple coincidence events (negative‐ion/positive‐ion/positive‐ion or NIPIPI coincidences) that were recorded with cleaner signals than those of the negative‐ion/positive‐ion coincidences. The intensities of the most intense NIPIPI coincidence channels were recorded as a function of photon energy across the C 1s and F 1s excitations and ionization thresholds. We also observed dissociation channels involving the formation of one negative ion and three positive ions. Our results demonstrate that negative‐ion/positive‐ion coincidence spectroscopy is a very sensitive method to observe anions, which at inner‐shell edges are up to three orders of magnitude less probable dissociation products than cations.

Publication forum classification

Field of science, Statistics Finland