By using UV spectra for the O star HD 93521 taken with the ORFEUS II echelle spectrograph , we determine an “ astrophysical ” f value for the S ii \lambda 94.7 nm line : f = 0.00498 { } ^ { +0.00172 } _ { -0.00138 } , error at 1 \sigma level .
This is almost a factor of 30 smaller than the guessed value found in the Kurucz database ( f = 0.1472 ) , which was up to now the only one available for this transition .
We use our “ astrophysical ” f to investigate the S abundance in two Damped Ly \alpha absorption systems ( DLAs ) observed with UVES at the ESO 8.2m Kueyen telescope .
In the case of the absorber at z _ { abs } = 3.02486 towards QSO 0347-3819 we find a sulphur column density which is consistent , within errors , with that determined by Centurión et al by means of the \lambda 125.9 nm line , thus providing an external check on the accuracy of our f value .
For the damped absorber at z _ { abs } = 4.4680 towards BR J0307-4945 we determine a high value of the S abundance , which , however , is probably the result of blending with Ly \alpha forest lines .