-ray absorption edges, of which there are three, as obtained by De Broglie in both uranium and thorium, so that the position in the Moseley table of each element all the way to the heaviest one, uranium, is fixed in this way by direct experiment. [Fig. 25] shows the progression of square-root frequencies as it appears from measurements made on the successive absorption edges of De Broglie’s photographs and on a particular one of Siegbahn’s emission lines. It will be noticed that, in going from bromine (35) to uranium (92), the length of the step does change by a few per cent. The probable cause of this will be considered later.
Fig. 22—X-ray absorption spectra.
series
Fig. 23—X-ray absorption spectra,
series