Decreased with chromium concentration curve

Magnetic susceptibility measurements were made on the several samples by the Gouy method. Susceptibility isotherms for two temperatures are shown in Fig. 9. These curves gives the susceptibility per gram of chromium in the several catalysts, as a function of chromium concentration. The expected rise of susceptibility with decreasing chromium concentration, and the position of point I are clearly shown, especially at low temperatures. In calculating the susceptibility of chromium in each sample it has been assumed that the susceptibilities of aluminum ions and oxide ions remain constant. This procedure is... 

The curves of Figure 2.9 exhibit the complex structure of the surface film. With increasing depth there is a peak of iron in the oxidized state at approximately 0.3 nm, and a peak of chromium in the oxidized state at about 1 nm irrespective of immersion time. The maximum concentration of oxidized iron decreases and the maximum concentration of oxidized chromium increases with increasing immersion time. 

In this instance, Cr Ka is the measured wavelength and it will be seen that both iron and chromium have very low absorptions for this wavelength. It will also be noted, however, that the Fe Ka line lies just to the short-wavelength side of the chromium absorption edge and is thus able to enhance Cr Ka. The calibration curve for chromium shows a positive deviation from linearity (i.e., decreasing slope with increasing analyte concentration) because as more chromium is added, there is less iron present to enhance the chromium. 

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