Auger decay mechanism in photon-stimulated desorption of ions from surfaces
Photon-stimulated desorption (PSD) of positive ions was studied with synchrotron radiation using an angle-integrating time-of-flight mass spectrometer. Ion yields as functions of photon energy near core levels were measured from condensed gases, alkali fluorides, and other alkali and alkaline earth halides. These results are compared to bulk photoabsorption measurements with emphasis on understanding fundamental desorption mechanisms. The applicability of the Auger decay mechanism, in which ion desorption is strictly proportional to surface absorption, is discussed in detail. The Auger decay model is developed in detail to describe Na/sup +/ and F/sup +/ desorption from NaF following Na(1s) excitation. The major decay pathways of the Na(1s) hole leading to desorption are described and equations for the energetics of ion desorption are developed. Ion desorption spectra of H/sup +/, Li/sup +/, and F/sup +/ are compared to bulk photoabsorption near the F(2s) and Li(1s) edges of LiF. A strong photon beam exposure dependence of ion yields from alkali fluorides is revealed, which may indicate the predominance of metal ion desorption from defect sites. The large role of indirect mechanisms in ion desorption condensed N/sub 2/-O/sub 2/ multilayers is demonstrated and discussed. Ion desorption spectra from several alkali halides and alkaline earth halides are compared to bulk photoabsorption spectra. Relative ion yields from BaF/sub 2/ and a series of alkali halides are discussed in terms of desorption mechanisms.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5458164
- Report Number(s):
- LBL-16892; ON: DE84004351
- Country of Publication:
- United States
- Language:
- English
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Auger decay mechanism in photon-stimulated desorption from sodium fluoride
Related Subjects
Molecular & Chemical Physics-- Beams & their Reactions
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
AUGER EFFECT
BARIUM COMPOUNDS
BARIUM FLUORIDES
CALCIUM COMPOUNDS
CALCIUM FLUORIDES
CALCIUM HALIDES
CATIONS
CHARGED PARTICLES
DESORPTION
ELEMENTARY PARTICLES
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
ION EMISSION
IONIZATION
IONS
LAYERS
LITHIUM COMPOUNDS
LITHIUM FLUORIDES
LITHIUM HALIDES
MASSLESS PARTICLES
PHOTOIONIZATION
PHOTONS
POTASSIUM COMPOUNDS
POTASSIUM FLUORIDES
SODIUM COMPOUNDS
SODIUM FLUORIDES
SURFACES