Effects of chemical combination on the X-ray LIIIabsorption limits of Mo, Rh, Pd, Ag and Cd

The shifts of the X-ray L III absorption limits of metallic Mo, Rh, Pd, Ag and Cd by chemical combination were measured with a curved quartz crystal spectrometer. The shifts are compared with those of the L III absorption limits of Cu, Ta, W, Au and Pb, and the K absorption limits of the elements from V to Zn observed by various investigators, and it is proposed that the shifts will be explained by considering mainly the two factors, (i) the selection rule for the appearance of the X-ray absorption limits assumed to correspond to transitions of electrons from the inner levels to the outer unoccupied levels of the lowest energy and (ii) the effect of the screening of the valence electrons for the outer levels.