Cliff-Lorimer factor

For a given detector and a given pair of elements the last two factors give a single constant (Icab) that can be treated as a relative sensitivity factor. Both that factor and the method obtained their names after the two people who introduced them, Cliff and Lorimer (1975). The simplicity originates from the fact that the Uab factor does not depend either on the rest of elements also present in the sample or on the other parameters of the sample (thickness, density), as far as the thin film criterion is fulfilled. The Cliff-Lorimer factors can either be calculated using the known parameters of the detector or can be measured if a well-characterized thin film sample (standard) is available. In the first case the method is standardless. In the second case the known weight fractions and the measured intensity ratio provides the Cliff-Lorimer factor for the pair of elements. 

Figure 7.4. Calibration curve of the Cliff-Lorimer factor = (Cx/Csi)(/si Ax) as a function of the Ka x-ray energy for an EDX detector for lOO-kV electrons. (From Cliff and Lorimer 1975.)...

EDS provides highly quantitative analysis of the local composition of elements, because the background intensity of the characteristic X-ray is very low in contrast to electron energy loss detected by EEiLS. The concentration ratio of two different elements (Ca/Cb) can be quantitatively determined by the ratio of peak intensities (/a//b) and J -factor or Cliff-Lorimer factor (La,b) as follows ... 

Capacity factor, 14 Capillary column, 4, 26 Carbowax, 33 Carrier gas, 23 CEC, 119 Cell constant, 70 Channeltron, 314 Chemical ionisation, 308 Chemical quenching, 224 Chemical shift, 138 Chemical vaporisation, 262 Chemiluminescence, 231 Chopper, 203 Chromatogram, 6 Chromogene, 194 Chromophore, 194 Cl, 308 CID, 200 Cliff-Lorimer, 248 Coefficient of variation, 387 Column (chromatographic), 28 Column 530 , 30 ... 

Atab. known as the Cliflf-Lorimer factor (Cliff and Lorimer 1975), contains all the factors needed to correct for the atomic number difference. 

Cliff-Lorimer sensitivity factor Kinetic energy... 

Cliff and Lorimer (1975) used this equation to form the basis for X-ray microanalysis of thin foils, where the constant kAB contains all the factors needed to correct for atomic number differences. kAB varies with operating voltage, but is independent of sample thickness and composition if the two intensities are measured simultaneously. Its value can be determined experimentally with accuracy, using specimens of known composition. The value of kAB can be determined by calculation more rapidly, but with less accuracy. 

---