CORRELATION-EFFECTS IN THE VALENCE X-RAY PHOTOIONIZATION SPECTRA OF ETHYLENE, BUTADIENE, AND HEXATRIENE

The x-ray photoemission spectra of the ethylene, butadiene, and hexatr iene compounds were investigated using one-particle Green's function c alculations which are exact up to third order in correlation. This stu dy points to the importance of initial-state correlation and cross-sec tion effects for a consistent reproduction of satellite bands recorded under X-ray photoionization. By extrapolating the results obtained to larger unsaturated hydrocarbons, it is clear that the signal recorded in the inner-valence region of polyacetylene must be exclusively assi gned to many-body structures. This study also provides evidence for a partial contamination of the outer-valence band by shake-up lines. (C) 1997 John Wiley & Sons, Inc.