The XUV photoabsorption spectrum of uranium vapour

The XUV photoabsorption spectrum of uranium vapour has been recorded by means of a novel, twin laser-produced plasma technique. The spectrum is dominated by a broad collective resonance and is in good agreement with recent predictions of many-body theory. Within the limits of experimental error, the widths and positions of the peaks are similar to those of the solid but show a slight shift with respect to those observed in UF 4 vapour. It is concluded that the 5f potential is largely unaffected on moving from the atom to the solid.