“…In the Ref. [19] the changes in the photoemission spectra of Gd, resulting from the exposure to the ambient gases (H 2 , CH x , H 2 O, CO and CO 2 ) at a total pressure of 5.0 × 10 −10 Torr, were monitored as a function of exposure time. The influence of oxidation upon the position and the shape of the Gd 4f and 4d peaks were observed within the interval shorter than 1 h. In this research, the 4d core level region spectra of Gd/EuTe multilayers structure were being recorded ∼2 h after the beginning of the measurements of XPS spectra set.…”