On the correct identification of shape resonances in NEXAFS

Using core level photoemission data from free molecules, it is shown that the putative shape resonances in NEXAFS can be identified unequivocally only by measuring the main line, or single hole, cross-section. This has important consequences for the characterisation of adsorbed molecules using NEXAFS where the technique is used to determine orientation and even intramolecular bondlengths.