Potential barrier minimum and delayed onset of continuous absorption beyond the 3d limit in Kr I

The 3d absorption spectrum of K r i has been studied photographically in the grazing incidence region. The substantially linear response of the photographic emulsion in the 50-130 Å wavelength range permits normalization of a photometric trace on to previous absolute cross section measurements. In addition to providing a reliable interpolation between the points, this procedure allows a determination of the energy of the absorption maxima and minima. Significant discrepancies between theory and experiment are revealed.