# Vacuum-Ultraviolet Negative Photoion Spectroscopy of SF5Cl

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## Abstract

Using vacuum-UV radiation from a synchrotron, gas-phase negative ions are detected by mass spectrometry following photoexcitation of SF$$_5$$Cl. F$$^-$$, Cl$$^-$$ and SF$$_5^-$$are observed, and their ion yields recorded in the range 8-30 eV. F$$^-$$ and Cl$$^-$$ show a linear dependence of signal with pressure, showing that they arise from unimolecular ion-pair dissociation, generically written AB + h$$v$$ $$\rightarrow$$ C$$^-$$ + D$$^+$$ (+ neutral(s)). F$$^-$$ is the strongest signal, and absolute cross sections are determined by calibrating the signal intensity with that of F$$^-$$ from SF$$_6$$ and CF$$_4$$. Resonances are observed, and assigned to transitions to Rydberg states of SF$$_5$$Cl. The Cl$$^-$$ signal is much weaker, despite the S-Cl bond being significantly weaker than the S-F bond. Appearance energies for F$$^-$$ and Cl$$^-$$ of 12.7 ± 0.2 and 10.6 ± 0.2 eV are determined. The spectra suggest that these ions form indirectly by crossing of Rydberg states of SF$$_5$$Cl onto an ion-pair continuum.

## Details

Original language English 8043-8048 6 The Journal of Physical Chemistry A 114 31 Published - 12 Aug 2010