Hook-method measurements of gf-values for ultraviolet Fe I and Fe II lines on a shock tube

Transition probabilities for 14 lines of Fe II and 12 lines of Fe I in the wavelength region 2560-2737 A were measured by use of a shock tube and the hook method. Absolute oscillator strengths for resonance lines of Fe I reported by Banfield and Huber were used to determine the number density of neutral iron in the shock-heated gas. With the assumption of thermal equilibrium, the density of singly ionized iron atoms in this gas was then computed from the measured temperature and pressure with the aid of the Saha equation. Our results on the 12 strongest of the 13 lines belonging to the first ultraviolet multiplet of Fe II indicate that the multiplet f-value is larger by a factor of 2 than that derived from lifetime measurements by Assousa and Smith.