Figure 3
(a) Diagram showing the TEY and FY processes. Straight arrows indicate scattered secondary electrons. The brightly shaded areas show the relative probing depths of the two detection modes. Electrons created deeper in the samples are less likely to escape the sample and reach the detector. Photons have longer scattering paths. (b) Relative XAS intensity as a function of depth for TEY (black, λ ≃ 1 nm) and FY (red, λ ≃ 1 µm). Note that the FY signal is nearly a bulk average over the range of our thin films because of the longer scattering path. As an example, the contribution to the TEY signal for a two-layer film is shown in shaded green areas. |