Chloroethane physisorbed on hydrogenated Si(111): A test system for the evaluation of core level XPS assignment rules at Si/SiO2 interfaces

We briefly review the controversy concerning the proper methodology for the assignment of soft x-ray photoemission Si 2p core levels at Si/SiO2 interfaces. Evidence for Second nearest neighbor effects in the photoemission spectra of analogous free molecules in the gas phase are surveyed for the purpose of placing this controversy within a wider context. Physisorption experiments have been performed to inquire whether the second nearest neighbor effects found in free molecules are in any way reduced in their magnitude owing to the proximity to the highly polarizable Si surface. No evidence for such a diminution have been found.