Correlation in the Auger spectrum of polyethylene

The Auger spectrum of polyethylene has been obtained on an energy scale calibrated relative to the threshold of the valence band and independent of problems associated with energy calibration and charging. The spectrum has a broad, featureless shape which has been previously interpreted in terms of a perturbed self-fold of the density of states. The calibrated C(KVV) spectrum reported here, however, is shifted by at least 10 eV relative to a perturbed self-fold of the density of states. This spectral shift requires a hole-hole correlation energy of at least 10 eV if one assumes that the threshold region reflects normal Auger transitions and >10 eV if the threshold region involves shakeup processes. Similar results are observed for the class of saturated linear alkanes. This behavior is shown to be inconsistent with recently calculated spectra for polyethylene in which small values of Ueff (1.2 eV for the C-C subband and 3 eV for the remaining contributions) were used to distort the self-fold of the density of states, and, moreover, inconsistent with any existing theoretical representation of Auger spectra. © 1989 The American Physical Society.