Ratio of the L_{3} to L_{2} Whiteline Intensity for 3d/4d Elements  Practical Electron Microscopy and Database   An Online Book  

Microanalysis  EM Book http://www.globalsino.com/EM/  
The two strong L_{3} and L_{2} white lines originate from the transition of electrons from the spinorbit split levels 2p_{3/2} and 2p_{1/2} to unoccupied 3d states. The ratio of the L_{3} to L_{2} whiteline intensity across the 3d series is theoretically expected to be 2:1 due to the statistical ratio of the initial states (four 2p_{3/2} electrons and two 2p_{1/2} electrons). In practice this ratio varies with atomic number (or d band occupancy) from 1:1 to about 4:1 [1]. In fact, the ratio and energy position of the L_{3} and L_{2} lines are significantly dependent on the dband occupancy and thus on valence state of the transition element [2, 3]. Cosandey [4] summarized the previous investigations on manganese oxides in various valence states as shown in Figure 3374a [58]. All the four studies show that the L_{3}/L_{2} (Similar to the L_{3} and L_{2} peaks in Figure 3374b) intensity ratios from Mn EELS measurements increase as the Mn valence state decreases. However, some variation exists among the studies due to the differences of the energy resolutions of particular EELS systems and of the methods used to extract the ratios. Therefore, for quantitative analysis, those potential instabilities need to be taken into account when we compare the results obtained from lab to lab.


