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Background determination in wavelength‐dispersive electron microprobe analysis: Some difficulties and presentation of a new analytical model
Author(s) -
Fialin Michel
Publication year - 1992
Publication title -
x‐ray spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.447
H-Index - 45
eISSN - 1097-4539
pISSN - 0049-8246
DOI - 10.1002/xrs.1300210406
Subject(s) - electron microprobe , analytical chemistry (journal) , wavelength , chemistry , valence (chemistry) , valence electron , electron , trace element , matrix (chemical analysis) , matrix element , atomic physics , physics , mineralogy , optics , organic chemistry , chromatography , quantum mechanics , particle physics
A background (BG) model is proposed for the determination of minor and trace element compositions with an electron microprobe (wavelength‐dispersive spectrometry). This model is particularly useful when a major band partially overlaps the peak corresponding to the element of interest. Its relationship is derived from a second‐order polynomial and can be written as B v = ( B 1 + B 2 )/2 + (1 + K BG )( B 2 − B 1 )/4, where B 1 and B 2 represent BG measurements to be performed on two symmetrical positions with respect to the analysed peak and K BG is a coefficient to be determined on a standard (BG standard) free from the sought‐for element but containing the overlapping peak. No BG standard with an approaching unknown matrix composition is required. An important feature is the shape of the overlapping band, which should be identical in both standard and unknown (at least within the energy range where measurements are performed). This last point is discussed using the example of elements whose analysed peaks are situated close to the Kβ 1, 3 bands of transition metals. The shape of such bands, which are related to valence states in the x‐ray emission processes, depends on the atomic chemical environment. Ti and Cr Kβ 1, 3 profiles, emitted from pure metals and some oxides, are usefully compared in this respect. The capabilities of the model were tested on the determination of Mn in Cr‐rich compounds (Cr Kβ 1,3 strongly overlaps Mn Kα).