High resolution photoabsorption spectroscopy at the carbonK-Edge

Using plane grating, ellipsoidal mirror, grazing incidence monochromators at the storage ring BESSY, a resolution of 150meV was achieved for a photon energy of 285 eV. This high energy resolution considerably extends the range of possible studies using core level Spectroscopy. Some of the new opportunities are illustrated at the CK edge by resolving the vibrational fine structure of condensed C₂H₄ multilayers in the (1s^–1, ^*) state by means of photoabsorption spectroscopy. For the sake of comparison with other high resolution instruments, the vibrational fine structure of condensed N₂ multilayers at the NK edge ( 400eV) was also measured, yielding a resolving power of 3000.