Background Measurement and Correction

High-purity copper is one of the important materials used in electrical devices, and the content of several trace elements has to be controlled carefully, as they have a significant influence on the quality and the properties of the product. Huang et al. [67] investigated the use of HR-CS F AAS for this purpose because of the superior detection power of this technique and the improved background measurement and correction capabilities. The authors found the well-known direct line overlap between the weak copper line at 213.853 nm... 

Moreover, as the entire radiation passes through the atomizer, any temporal change in the transmittance, for example of the flame gases, is corrected in the same way, a feature that is obviously not available in an optical double-beam system. This function is of particular importance for the measurement and correction of background absorption, which will be treated in detail in Section 5.2. 

There are several techniques available with LS AAS to measure and correct background absorption, such as deuterium (D2) background correction (BC), Zeeman-effect... 

In the case of a crystalline phase in an amorphous matrix, a rough measure of their ratio can be obtained if the compositions are known. This is accomplished by summing the powder diffraction line intensities, subtracting the amorphous (background) intensity, and correcting for Compton-modified scattering. The fact that there is a continuous spectrum of order from well-crystallized to noncrystalline phases is an inherent limitation to the method. 

Multichannel instruments are capable of measuring the intensities of the emission lines of up to 60 elements simultaneously. To overcome the effects of possible non-specific background radiation, one or more additional wavelengths may be measured and background correction (see Section 21.12) can be achieved. 

Integral intensities were obtained after dead-time corrections, background subtraction and normalization to averaged monitor counts. The Lp correction was applied in the usual way. Since the polarization ratio was not measured at BW5 so far, 90% linear horizontally polarized radiation was assumed for all scans. Calculations show that even a change in the beam polarization of 10% would effect the intensities of the highest order reflections of less than 1.5%. 

Rarely will it be possible to draw conclusions directly from the raw data of analytical measurements and it is usual for some refinement of the data to be carried out. In its simplest form this could merely comprise background corrections, but it is often much more complex, requiring corrections for a number of factors as in mass spectrometry, X-ray fluorescence and electron probe microanalysis. More complex routines made available by computers include spectrum smoothing, stripping one component from a spectrum or making peak area measurements from chromatograms. 

A measurement or observation in which the sample is replaced by a simulated matrix, the conditions otherwise being identical to those under which a sample would be analysed. Thus, the blank can be used to correct for background effects and to take account of analyte other than that present in the sample which may be introduced during the analysis, e.g. from reagents. 

---