Angle-resolved photoion spectroscopy of NO2 and SO2

Based on recent conceptual and technological improvements for soft X-ray monochromators, a varied-line-spacing plane grating monochromator of the Hetrrick type is installed on the bending-magnet beamline BL4B in the UVSOR facility with a second generation VUV ring of the beam energy of 0.75 GeV. The BL4B has enabled us to realize various spectroscopic investigations under high resolution conditions in the energy range of 90-800 eV. High-resolution angle-resolved photoion-yield spectra (ARPIS) of NO2 and SO2 have been measured in the N and O K-shell excitation regions. The fragment-ion yield spectra measured at 0degrees and 90degrees relative to the electric vector of the light reveal excitation symmetries of complicated electronic states. The spectral features are interpreted in comparison with other transition systems, and quantum chemical calculations show strong or weak Rydberg-valence mixing depending on the excitation site in the molecule. (C) 2002 Elsevier Science B.V. All rights reserved.