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Background corrections for electron probe dispersive analysis and resolution of overlapping peaks by Gaussian extrapolation
Micron, 1978, Vol.: 9. p. 13. c PergamonPress Ltd. Printed in Great Britain
0047-7206/78/0301~)013 $02.00/0
BACKGROUND CORRECTIONS FOR ELECTRON PROBE DISPERSIVE ANALYSIS AND RESOLUTION OF OVERLAPPING PEAKS BY GAUSSIAN EXTRAPOLATION DENNIS W . FOREMAN a n d ELEANORE AWADALLA The Ohio State University College of Dentistry, 305 West Twelfth Avenue, Columbus, OH 43210, U.S.A.
A method has been developed for determining background radiation obtained during energy dispersive analyses and correcting the data thereby for inclusion into a general intensity correction program such as Colby's (1968); additionally, the method is capable of resolving overlapping X-radiation intensity peaks under certain conditions and preparing the resolved, background-corrected data for subsequent program assimilation on a region-of-interest basis. Use of the method has been successful in reducing analytical data from microscopic studies of calcified tissues because of the coincidence of the bremsstrahlung maximum with such critical regions as the phosphorus K-alpha peak, and the fact that this method can be directed to emphasize sampling precision in that region, in practice, sampled background data are used to determine the coefficients of a quartic expression normalized at the short wavelength limit corresponding to the electron beam employed; corrections are then made channelby-channel and summed to the region of interest. The resolution of overlapping peaks is accomplished by a least-squares characterization of the coefficient and exponential factor of the Gaussian distribution expression applied to the
major and minor peaks which are involved in the overlap. The condition for use is that the minor peak must be uninvolved to the extent of half-width-at-half-maximum. In practice, the data are taken directly from the multi-channel analyzer on electronic data processing cards or tape and formatted to the program described above; output data are also formatted to feed directly to the general intensities correction program. An additional capability of the program is spotting small peaks hidden completely by larger ones. This is achieved simply by comparison of the experimental gross counts per channel with the summation of all contributions calculated from characterization of known peaks by the method described above. Data are presented substantiating the applicability of the method in the case of an investigation of the isomorphous substitution of strontium for calcium in the calcified tissues of rats fed low calcium high strontium diets.
REFERENCE Colby, John W., 1968. In: Advances in X-ray Analysis Vol. II, Plenum Press, N.Y., pp. 287.
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0047-7206/78/0301~)013 $02.00/0
BACKGROUND CORRECTIONS FOR ELECTRON PROBE DISPERSIVE ANALYSIS AND RESOLUTION OF OVERLAPPING PEAKS BY GAUSSIAN EXTRAPOLATION DENNIS W . FOREMAN a n d ELEANORE AWADALLA The Ohio State University College of Dentistry, 305 West Twelfth Avenue, Columbus, OH 43210, U.S.A.
A method has been developed for determining background radiation obtained during energy dispersive analyses and correcting the data thereby for inclusion into a general intensity correction program such as Colby's (1968); additionally, the method is capable of resolving overlapping X-radiation intensity peaks under certain conditions and preparing the resolved, background-corrected data for subsequent program assimilation on a region-of-interest basis. Use of the method has been successful in reducing analytical data from microscopic studies of calcified tissues because of the coincidence of the bremsstrahlung maximum with such critical regions as the phosphorus K-alpha peak, and the fact that this method can be directed to emphasize sampling precision in that region, in practice, sampled background data are used to determine the coefficients of a quartic expression normalized at the short wavelength limit corresponding to the electron beam employed; corrections are then made channelby-channel and summed to the region of interest. The resolution of overlapping peaks is accomplished by a least-squares characterization of the coefficient and exponential factor of the Gaussian distribution expression applied to the
major and minor peaks which are involved in the overlap. The condition for use is that the minor peak must be uninvolved to the extent of half-width-at-half-maximum. In practice, the data are taken directly from the multi-channel analyzer on electronic data processing cards or tape and formatted to the program described above; output data are also formatted to feed directly to the general intensities correction program. An additional capability of the program is spotting small peaks hidden completely by larger ones. This is achieved simply by comparison of the experimental gross counts per channel with the summation of all contributions calculated from characterization of known peaks by the method described above. Data are presented substantiating the applicability of the method in the case of an investigation of the isomorphous substitution of strontium for calcium in the calcified tissues of rats fed low calcium high strontium diets.
REFERENCE Colby, John W., 1968. In: Advances in X-ray Analysis Vol. II, Plenum Press, N.Y., pp. 287.
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