Bombardment Induced Electron-Capture Processes at Sodium Halide Surfaces.

Area of Science:

• Solid-state physics
• Surface science
• Atomic and molecular physics

Background:

• Ion-surface interactions are crucial for understanding material modification.
• Electron emission spectroscopy reveals surface electronic states.
• Sodium halide surfaces exhibit complex deexcitation processes under ion bombardment.

Purpose of the Study:

• To elucidate the mechanism behind discrete electron energy features observed in ion-bombarded sodium halide surfaces.
• To propose a new model for collisional deexcitation involving autoionizing states.
• To investigate the role of localized electron transfer in inelastic ion-surface collisions.

Main Methods:

• Analysis of discrete features in electron energy distributions.
• Theoretical modeling of collisional deexcitation processes.
• Investigation of cascade collisions within the crystal lattice.

Main Results:

• Identified a new collisional deexcitation mechanism involving sodium atoms in bombardment-excited autoionizing states.
• Demonstrated that deexcitation is a sequence of lattice collisions, not solely dependent on initial ion lifetime.
• Observed the formation of inner-shell-excited Na0* states responsible for observed transitions.

Conclusions:

• The new model accurately describes the formation of autoionizing Na0* states.
• Localized electron-transfer mechanisms open new channels for deexcitation, dissociation, and defect production.
• Understanding these processes is critical for inelastic ion-surface collisions in solids.