Observed spectra with the VTT. The upper spectrum corresponds to an average quiet-Sun profile (QS), whereas the lower spectrum represents one profile within the sunspot (SP), roughly at the center of the umbra. The SP spectrum is an average over five spectral pixels using a Lee-filter, available on the Interactive Data Language (IDL) with the routine leefilt.pro, an algorithm used to reduce the noise. The splitting of the spectral lines is clearly visible in the strong sunspot field. Lines marked with a star (*) are used as the main lines in the inversions. All other lines are considered as blends in the Stokes Inversion based on Response functions (SIR) code. The atomic parameters for each line are listed in Table 1.