Extended x-ray emission fine structure and high-energy satellite lines state measured by electron probe microanalysis

The K alpha satellite or shake-off lines can be observed by wavelength-disp ersive spectrometry on the high-energy side of the main K alpha peak. Occas ionally, chemical state analysis of an emitting atom has been attempted usi ng the shape and position of these lines. Recent extensive theory and exper iment have shown that it is fruitful to take a similar approach using exten ded x-ray emission fine structure (EXEFS) arising from the radiative Auger effect (RAE). This fine structure is found in a low-intensity spectrum on t he low-energy side of the Ka peak. We have studied the RAE spectra of the Ka lines of the elements F through t o Ca by EPMA. The RAE peaks have energies close to the KLL energies of Auge r transitions. In the lighter elements in this series, it was found that th e difference between Ka and the RAE peak energies becomes quite small. For elements lighter than fluorine, it is difficult to observe the RAE peaks be cause they are overlapped by the main Ka line. At the higher energy end of the series, the intensity of the RAE lines becomes very small. The utility of the RAE lines for state analysis is limited, in practice, to the element s F through to Ca. The extended x-ray emission fine structure (EXEFS) of th e RAE spectra has been used to calculate local bonding parameters. Both shake-off and RAE spectra associated with the F Ka line have been stud ied experimentally in the rare earth fluorides. The KLL RAE moves to lower energy as the atomic number of the rare earth cation increases. This has be en confirmed theoretically by calculating electron energies using discrete variational X alpha molecular orbital theory. The shake-off peaks increase in intensity relative to the main K alpha peak because atomic number increa ses, contrary to expectation. It is considered that this could be due to te mporary covalency. The EXEFS of the RAE spectra has been used to calculate local bonding parameters. Copyright (C) 2001 John Wiley & Sons, Ltd.