Different Processes for Desorption of Ground- and Excited-State Atoms Under Electron Bombardment of Alkali-Halides

1990 ◽  
pp. 289-296 ◽  
Author(s):  
P. Wurz ◽  
J. Sarnthein ◽  
W. Husinsky ◽  
G. Betz
Keyword(s):  
Excited State ◽  
Alkali Halides ◽  
Electron Bombardment

EPR Study of the Relaxed Excited State of F-Centres in Alkali Halides

1982 ◽  
Vol 110 (1) ◽  
pp. 89-96 ◽  
Author(s):  
N. G. Romanov ◽  
Yu. P. Veshchunov ◽  
V. A. Vetrov ◽  
P. G. Baranov
Keyword(s):  
Excited State ◽  
Alkali Halides

Excited-Atom Production by Electron Bombardment of Alkali-Halides

1986 ◽  
Vol 75 ◽  
Author(s):  
R. E. Walkup ◽  
Ph. Avouris ◽  
A. P. Ghosh
Keyword(s):  
Gas Phase ◽  
Excited States ◽  
Ground State ◽  
Excited Atom ◽  
Alkali Halides ◽  
Electron Bombardment ◽  
Secondary Electrons ◽  
Excited Atoms ◽  
Positive Ions ◽  
Electronically Excited

AbstractWe present experimental results which suggest a new mechanism for the production of excited atoms and ions by electron bombardment of alkali-halides. Doppler shift measurements show that the electronically excited atoms have a thermal velocity distribution in equilibrium with the surface temperature. Measurements of the absolute yield of excited atoms, the distribution of population among the excited states, and the dependence of yield on incident electron current support a model in which excited atoms are produced by gas-phase collisions between desorbed ground-state atoms and secondary electrons. Similarly, gas-phase ionization of ground-state neutrals by secondary electrons accounts for a substantial portion of the positive ions produced by electron bombardment of alkali-halides.

The detachment of electrons from negative ions

1954 ◽  
Vol 222 (1148) ◽  
pp. 74-83 ◽  
Keyword(s):  
Excited State ◽  
Cross Sections ◽  
Ground State ◽  
Thermal Dissociation ◽  
Negative Ions ◽  
Electron Bombardment ◽  
Rare Gas ◽  
Ion Energy ◽  
Rare Gas Atoms ◽  
Long Lifetime

Detachment cross-sections for collisions of O - , Cl - , F - ions with rare-gas atoms are measured between 50 and 4000 eV incident-ion energy. The negative ions are produced (i) by thermal dissociation of molecules at a filament, followed by radiative attachment into the ground state; (ii) by electron bombardment of molecules, giving ions previously believed to be in an excited state of long lifetime. In every case the detachment cross-sections for the ions produced in the two ways are the same, so that we must conclude either (i) that the excited state has a short lifetime which is unlikely but not impossible, or (ii) that no excited state exists, and that the appearance potentials for ions believed to be in this state must be explained by another process, such as the formation of O neutrals followed by radiative attachment at the source filament.

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