Desorption of doubly excited autoionizing Li from LiF/Si(1 0 0) under electron bombardment

Abstract

We report measurements of electron-stimulated desorption of core-excited autoionizing states of lithium from an LiF surface. In the time-of-flight spectrum a delayed signal of Li+ is observed. Its analysis indicates that at least three autoionizing transitions are active in the Li+ desorption process. They are as follows: Li**(1s 2p2)4P5/2→Li+(1s2)1S with a lifetime of (379±9)ns, Li**(1s 2p2)4P5/2→Li**(1s 2s 2p)4P5/2,3/2 with a lifetime of (8.3±0.8)ns, Li**(1s 2s 2p)4P5/2→Li+(1s2)1S with a lifetime of (5.2±0.3)μs, and Li**(1s 2s 2p)4P3/2→Li+(1s2)1S with a lifetime of (301±2)ns. The relative contributions of Li**(1s 2s 2p)4P5/2 and Li**(1s2s2p)4P3/2 components are equal to 0.33±0.02 and 0.67±0.02, respectively. Our lifetime values are consistent with those obtained by other experimental methods. Possible processes leading to the desorption of core-excited Li atoms are discussed.