1910] 



on X-Rays and Atomic Structure 



72?> 



and state of an L electron ; by analogy it may be concluded that a 

 qaantam of L radiation is the energy required to move an electron 

 from the position and state of an L electron to the position and 

 state of an M electron. 



We also find a quantum of K radiation is emitted for each K 

 electron ejected, as shown in the Table :— 



Number of quanta of 



K fluorescent radiation emitted 



per K electron ejected. 



1-09 

 0-95 

 0-85 

 0-81 

 0-90 



With primary radiation of just shorter wave-length than that of the 

 K radiation, for each electron emitted there is absorbed the energy 

 «of a quantum of K radiation as well as that carried away by the 

 electron ; therefore each absorbing atom has absorbed about two 

 quanta of prirnarij radiation. As A. decreases, the energy absorbed by 

 each atom is that of one quantum of primary radiation (going to an 

 electron) plus the energy of one quantum of secondary characteristic 

 radiation (going to the fluorescent characteristic radiation). This 

 varies from the energy of two quanta to that of one quantum of 

 the primary radiation as the wave-length diminishes. Absorption, 

 therefore, is not in whole quanta. 



There is thus again no evidence of an entity or indivisible quan- 

 tum of radiation even in the phenomena supposed to strongly support 

 such a theory. The reason why it has usually been supposed that 

 energy is absorbed in quanta is that the second part is frequently 

 small ; it may, however, be any fraction of another quantum of 

 primary radiation. 



A¥e have shown that the emission of each electron of the cor- 

 puscular radiation is associated with the emission of a quantum of 

 the corresponding fluorescent X-radiation, but there is conclusive 

 evidence that the electron, after emission, takes no part in the 

 phenomenon of fluorescence — that is, the emission of characteristic 

 radiation is entirely independent of the electrons after their emission. 

 We must, therefore, conclude that the atom which emits an electron 

 emits also a fluorescent radiation characteristic of the atom itself. 

 The observed relations lead to the following considerations : — 



When a K electron is hurled out of the atom it is possible that 

 for stability another electron must fall into the position and state 

 of the K electron. If it falls from the position and state of an L 

 electron, the excess energy, which is that of a quantum of K radia- 



3 B 2 



