Figure 4
Linear combination analysis of XANES spectra at the Cu K-edge of a Cu/Al2O3 catalyst during an applied gas flow alternating each 60 s between 21%-O2/He and 5%-H2/He. The normalized 3714 sample spectra were least-square fitted by a linear combination of normalized reference spectra of Cu (red), Cu2O (green) and CuO (blue). Fractions of each Cu species are plotted in T-REX as a function of spectrum number, whereby ten spectra correspond to 1 s acquisition time in this example. The reproducible sample variation between more reduced and more oxidized copper species can be easily followed here. |