Figure 4.

In situ X-ray photoelectron spectra of the C 1s (A), Ni 2p (B), and O 1s (C) regions obtained during exposure of the Ni foam to 0.02 mbar methane at the indicated temperatures after the standard sample pretreatment described in Figure 1. Photon energies: 425 eV (C 1s), 1010 eV (Ni 2p), 680 eV (O 1s). Collecting one set of C 1s, Ni 2p, and O 1s at a given temperature takes ca. 30 min.