A. Kuczumow et al., Application of auxiliary signals in X-ray fluorescence and electron microprobe analysis for density evaluation, X-RAY SPECT, 28(4), 1999, pp. 282-291
Information included in auxiliary signals, i.e. incoherently and coherently
scattered signals and transmitted beam intensities in x-ray fluorescence a
nalysis (XRF), a selected channel in the scattered white synchrotron radiat
ion and in the contents of selected bremsstrahlung channels in electron mic
roprobe analysis (EMPA), can be extracted and exploited to complete the res
ults of analyses. Such additional information is much more detailed when th
e devices are operating in the microprobe mode; however, this is not a nece
ssary condition. The theoretical basis for the use of the auxiliary signals
, in the sense proposed in this paper, is discussed. In situations where th
e main component is of essentially constant chemical composition but with v
ariable density through the sample (wood of living trees, petrified wood, s
talactites, coral structures-in general natural periodic structures) or wit
h inclusions inside, the application of two kind of signals is preferable i
n XRF: the transmitted and scattered signal. For light organic matrices (ce
llulose, plastics), the information included in the Rayleigh or Compton sig
nal is reversed in relation to the information from the transmission signal
s. The selected bremsstrahlung signal or the signal from the secondary elec
tron spectrum can serve the same purpose if EMPA analysis is performed. In
general, these signals provide auxiliary knowledge about the density of obj
ects. An especially interesting situation is when the object is a chemical
negative of the original, such as the distribution of silica in some kinds
of petrified wood with respect to the distribution of the cellulose in the
original wood. Many original results of analyses are shown. Intercomparison
s of the transmission images with the reversed scattered scans in light mat
rices are still scarce, while the observation of bremsstrahlung or secondar
y electron scans (in EMPA) and their scattered or transmission analogues (i
n XRF) for objects and their chemical negatives is demonstrated for the fir
st time. Comprehensive results of the analyses of petrified wood and stalac
tites (EMPA and XRF) are presented. Copyright (C) 1999 John Wiley & Sons, L
td.