Influence of thermal annealing on the properties of multilayer Mo/Be mirrors

The influence of thermal action on X-ray optics performance and structure of films and transition regions in multilayer Mo/Be mirrors optimized for a reflection maximum in the interval 11.2–11.4 nm at normal incidence has been considered. The annealing temperature reached 300$^{\circ}$C and the annealing time was 1 and 4 h. It has been shown that after thermal annealing in vacuum for 1 h at 300$^{\circ}$C, the reflection coefficient rises; however, when the annealing time grows to 4 h, it drops. Grains in molybdenum films become finer, and the profiles of transition regions change from exponential to linear. The period of multilayer mirrors has remained the same under all annealing conditions.