Ionic Crystal Decomposition with Light
Abstract
We report on RbI crystal decomposition due to electronic excitations in a vicinity of the top of the crystal band gap by UV photon irradiation. Dynamic Force Microscopy (DFM) studies reveal that randomly spread rectangular pits of monolayer depth in the topmost layer of the crystal are formed during irradiation. Growth and coalescence of the pits lead to almost `layer-by-layer' desorption mode. Similarly to electron stimulated desorption, periodic changes of surface topography were found to have a profound effect on the desorption process. Since excited F-centre recombination with alkali atom emission was possible exclusively at low-coordinated sites the desorption yields were found to go hand in hand with the number of low-coordinated sites on the surface. Furthermore, simultaneous irradiation of the crystal by UV photons and visible light within the F-centre absorption band increases average F-centre mobility which has a profound effect on process efficiency. Such processes could be applied in controlled surface nanostructuring.
- Publication:
-
Acta Physica Polonica B
- Pub Date:
- August 2002
- Bibcode:
- 2002AcPPB..33.2237S