Measurement of the photodetachment cross section of the negative ion of fluorine

The photodetachment cross section of ${\mathrm{F}}^{\mathrm{-}}$ was obtained experimentally from a stationary arc plasma of ${\mathrm{SF}}_6$ at atmospheric pressure. The temperature was determined by spectroscopy. The electron number density was measured by two-wavelength laser interferometry and by emission spectroscopy. Departures from local thermodynamic equilibrium were taken into account. The variations of the photodetachment cross section of ${\mathrm{F}}^{\mathrm{-}}$ versus wavelength were obtained by measuring the absolute intensity of the continuum radiation emitted by the plasma and are compared with results from the literature.