Fig. 4: XPS at near-ambient pressures.

C1s spectra recorded during exposure of an acetylene-covered Co(0001) surface to increasingly high H2 pressures at T = 313 K. The time evolution of the C1s spectra is shown in the lower panel, whereas the top view shows the spectra at specific stages of the experiment (hν = 420 eV). Note that the signal intensity of the acetylene spectrum in the upper panel was divided by two to facilitate comparison.