High-Resolution Photoionization Of Core-Excited Atoms And Molecules Using Synchrotron-Radiation

We report on the recent progress in high-resolution photoabsorption studies of atoms and small molecules in the soft X-ray region, using synchrotron radiation from the SX700/II monochromator at BESSY. In the double-excitation region of He and Ne (2p-2), new Rydberg series and interseries interference phenomena were observed. For a number of diatomic and small polyatomic molecules, C1s, N1s, O1s, S2p, and Cl2p core-excitation spectra were measured, which reveal fine structure due to vibrational sidebands, vibronic coupling, and molecular splitting in the excited state.