Angular Distribution of Photoemission from Surfaces of Amorphous Solids |
| A. Jabłoński Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland |
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| As follows from the formalism of X-ray photoelectron spectroscopy, knowledge of the angular distribution of photoemission is crucial for certain applications of quantitative X-ray photoelectron spectroscopy analysis. In the present work, the experimental data on the relative angular distribution of photoemission from solid materials are reviewed and compared with theoretical predictions. Noticeable discrepancies are usually observed. It has been proved that major part of the observed discrepancies can be ascribed to elastic photoelectron scattering. The commonly used formalism, where the elastic collisions are neglected, may be of insufficient reliability for certain solids, or in certain experimental geometries. This formalism can be easily extended to account for elastic photoelectron collisions by introducing two correction factors, QX and βeff. The second parameter, called the effective asymmetry parameter, describes the observed decrease in anisotropy of photoemission. Determination of the correction factors requires a reliable theory describing elastic electron scattering in the solid. A need arises for accurate differential and total elastic electron scattering cross-sections pertinent to kinetic energies of considered photoelectrons or the Auger electrons. The increasingly important role of electron transport in surface analysis has stimulated an effort to construct a complete database containing the differential and total atomic elastic scattering cross-sections. |
| DOI: 10.12693/APhysPolA.86.787 PACS numbers: 79.60.-i, 72.10.-d, 34.80.Bm |