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Excitation-Energy-Dependent Resonances in Soft X-Ray Appearance Potential Spectra of the Cerium 4d- and 3d-Electron Levels

Published online by Cambridge University Press:  06 March 2019

M. B. Chamberlain  and
W. L. Baun
M. B. Chamberlain*
Affiliation:
Air Force Materials Laboratory, MBM, Wright-Patterson Air Force Base, Ohio 45433
W. L. Baun
Affiliation:
Air Force Materials Laboratory, MBM, Wright-Patterson Air Force Base, Ohio 45433
*
*Presently at McDonnell Douglas Research Laboratories, P.O. Box 516, St. Louis, Mo. 63166
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Abstract

When the excitation energy lies near the ionization potential of many core electrons, core-hole relaxation effects strongly affect x-ray emissions. Under near-threshold electron excitation of the cerium 4d subshell both the incident electron and a 4d-core electron are promoted into 4f-orbital excitation states which exist only during the life of and are bound to the 4d vacancy. The exchange interaction between the 4d hole and the excited electrons in the unfilled 4f subshe11 spreads the energies of the discrete excitation states over a 20eV range sending some levels well below the 4d threshold and others into the continuum. Exchange interactions and potential barrier effects have a dominant influence upon the cerium 4d and 3d soft x-ray appearance potential spectra reported in this paper. We observe sub-threshold x rays extending to 8.6eV below the binding energy of the 4d level as well as a maximum in the yield at 12eV above the 4d onset. As the electron excitation energy is swept through the thresholds of the two 3d levels we observe resonant x-ray emissions, while at 28eV above these levels we see plasmon loss structures.

Type
Research Article
Information
Advances in X-Ray Analysis , Volume 18: Twenty-Third Annual Conference on Applications of X-ray Analysis, August 7-9, 1974 , 1974 , pp. 415 - 424
Copyright
Copyright © International Centre for Diffraction Data 1974

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References

1. Park, R. L. and Houston, J. E., “Soft X-Ray Appearance Potential Spectroscopy,” J. Vac. Sci. Technol. 11, 1–18 (1974).Google Scholar
2. Park, R. L. and Houston, J. E., “L-Shell Soft-X-Ray Appearance-Potential Spectra of the 3d Transition Metals,” Phys. Rev. B6, 1073–1081 (1972).Google Scholar
3. Chamberlain, M. B., Burr, A. F., and Liefeld, R. J., “Excitation- Energy-Dependent Features in the Continuum Spectrum of Cerium near the Met and M$ X-Ray Emission Lines,” Phys. Rev. A9, 663–667 (1974).Google Scholar
4. Fomichev, V. A., Zimkina, T. M., Gribovskii, S. A., and Zhukova, I. I., “Discrete Absorption by 4d Electrons in the Lanthanum Group Rare-Earth Metals,” Sov. Phys. - Solid State 9, 1163–1165 (1967).Google Scholar
5. Haensel, R., Rabe, P. and Sonntag, B., “Optical Absorption of Cerium, Cerium Oxide, Praseodymium, Praseodymium Oxide, Neodymium Oxide, and Samarium in the Extreme Ultraviolet,” Solid State Commun. 8, 1845–1848 (1970).Google Scholar
6. Sugar, Jack, “Potential-Barrier Effects in Photoabsorption. II. Interpretation of Photoabsorption Resonances in Lanthanide Metals at the 4d-Electron Threshold,” Phys. Rev. B5, 1785–1792 (1972).Google Scholar
7. Fomenko, V. S., Handbook of Thermionic Properties, Plenum Press, New York 1966, pages 75-76.Google Scholar
8. Bearden, J. A. and Burr, A. F., ‘'Reevaluation of X-Ray Atomic Energy Levels,” Rev. Mod. Phys. 39, 125–142 (1967).Google Scholar
9. Houston, J. E. and Park, R. L., “Effect of Oxygen on the Soft X-Ray Appearance Potential Spectrum of Chromium,” J. Chem. Phys. 55, 4601–4606 (1971).Google Scholar
10. Chamberlain, M. B. and Baun, W. L., “Excitation-Energy-Dependent Resonances in Bremsstrahlung X Rays under Near-Threshold Electron Excitation of the Cerium N4,5, M4, and M5 Levels,” submitted to Phys. Rev. A, March, 1974.Google Scholar
11. Zimkina, T. M., Fomichev, V. A., Gribovskii, S. A., and Zhukova, I. I., “Anomalies in the Character of the X-Ray Absorption of Rare-Earth Elements of the Lanthanide Group,” Sov. Phys. - Solid State 9, 1128–1130 (1967).Google Scholar
12. Gudat, W. and Kunz, C., “Close Similarity between Photoelectric Yield and Photoabsorption Spectra in the Soft X-Ray Range,” Phys. Rev. Lett. 29, 169–172 (1972).Google Scholar
13. Nilsson, P. O. and Kanski, J., “Appearance Potential Spectroscopy of Simple Metals,” Surface Sci. 37, 700–707 (1973).Google Scholar