Evidence for the occurrence of a nitrogen-induced reconstruction of W{100} was presented from a surface core level shift study of the W 4f 7/2 level using a new method of analysing core shift data, which related the centre of gravity of the spectrum to the coverage. It was deduced that, at low coverages, N adatoms caused a local displacement of surface W atoms; forming small contracted islands. At coverages greater than 0.3 monolayers, all surface W atoms were found to be bonded to at least one N adatom, and the appearance of large contracted domains deduced from low-energy electron diffraction patterns in the coverage range of 0.3 to 0.4 was consistent with the present data. Removal of surface reconstruction was observed between 0.4 and 0.5 monolayers. The surface core level shift induced in surface W atoms by bonding to one, two and three N adatoms were identified, and were consistent with charge transfer to the N.A Surface Core Level Shift Study of the Nitrogen-Induced Reconstruction on W{100}. J.Jupille, K.G.Purcell, D.A.King: Solid State Communications, 1986, 58[8], 529-33