VARIATION OF THE C(KVV) AUGER ANGULAR-DISTRIBUTION IN THE C(1S) SIGMA-ASTERISK-RESONANCE OF CO

We report on angle-resolved high-resolution measurements of C (KVV) Au ger spectra of CO in the vicinity of the C (1s) sigma-shape resonance above threshold. These spectra show clear evidence for the theoretica lly predicted anisotropic K-shell Auger emission in molecules. Complem entary results from angle-resolved photoion-spectroscopy show that the small size of the observed effect is, besides the varying intrinsic a nisotropy of the Auger decay, also due to a smaller anisotropy in the primary absorption process than originally predicted but in good agree ment with more recent calculations. Contrary to this, some satellite A uger transitions show large anisotropies outside the shape resonance, an effect attributed to a conjugate shakeup transition in the primary photoionization process. All Auger anisotropies show a clear and disti nct variation across the shape resonance which enables a distinction b etween different types of Auger transitions concerning the primary pho toionization process.