and the Theory of Atomic Structure. 



1085 



together on the photographic plate. For the lines measured 

 with a gypsum crystal we have to multiply the above given 

 limits of error by 1^-2. Thus far I have neglected the 

 errors in the wave-length which are due to the remarkable 

 fact detected by Stenstrom f that Bragg's relation rik = 

 2d sin <f> is only approximately true. Especially with a 

 gypsum crystal the deviations are fairly large and may give 

 rise to an error of several X-units, but as this error is nearly 

 the same for wave-lengths of about the same value it does not 

 affect the conclusions drawn in this paper. Tables I., II., III. 

 contain only the lines which can be arranged in diagram I. 



§ 5. The right classification of the lines often gives trouble. 

 Some indications were supplied by the relativity L-doublets, 

 which are given in Table IV. Down to Ag the Yr-/3 2 doublet 



Table IV. 

 Relativity L-doublets. 



i-l. 



0i- 



37 Eb. 



38 Sr . 



39 Y . 



40 Zr . 



41 Nb 



42 Mo. 



44 Uu. 



45 Rh. 



46 Pd. 



47 Ag. 



48 Cd. 



49 In . 



50 Sn . 



51 Sb . 



52 Te 



55 Cs . 



56 Ba. 



4-92 



6-15 



7-10 



1054 

 11-48 

 12-64 

 13-81 

 15-23 

 16-69 

 18-31 



27 69 



4-28* 

 4-80* 

 5-40* 

 603* 

 6-89 

 7-70 

 9-49 

 10-48 

 11-56 

 12-69 

 13-97 

 15-29 

 1671 

 18-29 

 19 94 

 2559 

 2774 



75-& 



4-48 

 500 



6-21 



9-53 

 10-41 

 11-66 

 12-77 

 13-98 

 15-26 

 16-77 

 18-26 

 2003 

 25-76 

 27-95 



7i-/ 



6-13 



6-99 



7-80 



947 



10-46 



11-57 



12-46 



13-92 



15-24 



16 60 



18-21 



19-85 



25-42 



27 61 



L 1" L 2- ! 



12-68 



(25-8) 

 2800 



* As # 2 could not be measured for tbis element, the value (3 l -x l has been 

 used. This value is smaller than /3 X — <9C 2 . 



difference is apparently smaller than the other ones J, lower 

 down this " doublet defect " disappears in the accidental 

 errors. The cause of this defect will be seen from diagram I. 

 The pairs of lines r)-l, fi\-a 2 , and y 5 -/3 6 come each from the 

 same initial level, whereas <y x and j3 2 come from different 

 initial levels. I have never observed the transition N 4 -L 1? 



t Stenstrom, Dissertation, Lund, 1919 ; Iljalmar, Zeitschr. f. Phys. i. 

 p. 439 (192U) ; Siegbahn, Comptes Rendus, clxxiii. p. 1350 (1922). 

 { Compare also Zeitschr. f. Fhys. II. table 3, p. 191. 



