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Updated: Jan 2, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Negative-ion/positive-ion coincidence spectroscopy as a tool to identify anionic fragments: The case of core-excited
Antti Kivimäki1,2, Christian Stråhlman2,3, Rami Sankari2,4
1Nano and Molecular Systems Research Unit, University of Oulu, 90014 Oulu, Finland.
Abstract:
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.
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