﻿Atomic Model with a Magnetic Core. 723 



But the significant point is that accompanying /Si— ft? we 

 have fJii — fo, suggesting that the quantity fju also depends on 

 the revolution of parts of the core in such a way that the 

 effects can be combined by simple addition or subtraction. 



For this to be the case, /x would have to be proportional 

 to the first power of the angular velocity, i.e. to the angular 

 momentum or to the magnetic moment of the part of the 

 ■core with which it is associated. Thus it should be possible 

 to express fx in terms of the magnetic moment, and it might 

 be possible to obtain some relation between jul and ft. 



liydberg has suggested that the correct expression for the 

 frequency of a line in a spectral series is some function of 

 t + /x, where t is an integer and fx is fractional. This view 

 has received strong support from Thiele, who maintained that 

 the wave-length was some function of (r-f yit) 2 , where r could 

 take all integral values, both positive and negative. Nichol- 

 son's recent critical investigation of the spectrum of helium 

 shows conclusively that in this case the frequency is a 

 function of r-{-/x. 



In Bohr's theory of the hydrogen spectrum, the angular 

 momentum of a bound electron is assumed to be constant and 

 equal to ilt'ftir. In order to obtain a theory applicable to 

 the spectra of other elements, it appears necessary to assume 

 that the angular momentum of the electron is (r + fx)h/'2rr. 

 In order to account for the presence of jx in this expression, 

 we assume that we must include with the angular momentum 

 of the electron that of the core, or more probably that of the 

 part of the core which is specially related to the electron. 

 Thus Ave make the total angular momentum of the electron 

 and the part of the core equal to rh/27r. 



Then mr 2 (o =p M = t1i!2it. 



So mr 2 a) — t1iJ2tt ± 111 



= (t ± fju)h/2ir, 

 where fx = ZirlfL/li. 



Proceeding on the lines of Bohr's theory we can then 

 obtain Rydberg's equation. 



The extension of the principle of the constancy of angular 

 momentum from the electron to the core, receives a measure 

 of support from the work of Bjerrum and others. Bjerrum 

 assumed that the energy or the momentum of a rotating 

 molecule could be expressed in terms of h. The experimental 

 results obtained from the absorption of infra-red radiation 

 by gases are in agreement with the results of his theory. 



The supposition that /x corresponds to the angular 

 momentum of only a part of the core was suggested by the 

 numerical values found in spectral series. It is intelligible 



3 A2 



