Detection angle dependence of the ratio of two oxide signals (IAl2O3 =ISiO2 ).
Inset
shows the schematic view of angle-resolved XPS and the sample structure.
Red points:Sample calcined at 600 °C. Black points: Sample calcined at 300 °C.
(For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)