Qualitative X-Ray Analysis

Abstract

• Identification of the elements. • EDX detection limit in bulk materials is about 0.1wt%. General definitions -less than 1wt% (trace), 1-10wt% (minor), 10wt% (major). • WDS can achieve limits of detection of 100 ppm in favorable cases, with 10 ppm in ideal situations where there are no peak interferences and negligible matrix absorption. • The spectral broadening effect for a 155-eV EDX spectrometer presented in Figure 6.1 is intended as an aid to estimate the possible peak overlaps. • Tables 6, 7 and 8 (check the CD included in the textbook) provide Kα, Lα, and Mα X-ray energy. Plot of the Energy of the X-Ray emission Lines Observed in the Range 0.75-10keV • When the beam energy exceeds the critical x-ray ionization energy for a shell or subshell so that it is ionized, all possible transitions involving that ionized shell may take place, producing a family of peaks, which will become more complicated as the electronic structure of the atom increases in complexity. The analyst must be familiar with the concept of a family of x-ray peaks. • With a beam energy of 15 keV or more, all possible lines of an element in the range of 0.1-10 keV will be efficiently excited. The presence in the spectrum of all possible members of a family of lines increases the confidence for the identification of that element.