SOME CONTF.MI'OR.IRV .IPr.lXCF.S IX rilYSlCS -llll 453 



as the K Kr<>»p. llu- L uroiip, the .\/ jjroiip and tin- .V nn>ii|). Tlu- 

 wuril series is mort- nunmoiily used tlian g,roiip: Ixii this is a inis- 

 fortuiic. for it suggests a daiiKerously misleading .m.ilony witli the 

 series in the optical spectra wliich we have studied with so much 

 care." The process of measiirinu these Hues and cl.issifyinj; them 



f!t,*^?i 





IM 



m 



L Muii-W 'i-xMM^Hi.iSt 





/»:^^ 

 *, ^ 



1^ 



/ViVfl, /( y 



EE 



4im. 



■/. d 



■ z, b 



Kig. 13— Diagram of stationan,- states designed to account for the X-ra\- si)cctriir 

 of uranium. (From Sicgbahn, after Coster) 



was carried out after the dissemination of Bohr's great idea that 

 each line-frequency should be multiplied by // and the product in- 

 terpreter! as the difference between the energy-values of two stationar> 

 states of the atom. The complete analysis of an X-ray spectrum 



"In fact the usage is inverted. A series, in the optical spectrum, is a set of lines 

 havmg the same jinal state in common; but the " k-series" is a group of lines having 

 the same initial state in common, the L-series a set of 3 groups corresponding to 3 

 initial states. 



