X-ray Electrons. 1125 



In the table are shown the equivalent frequencies of the 

 X-ray electrons for the eight elements examined. 



In the second column is indicated the position within 

 the atom from which the electron maybe supposed to come; 

 while the third column shows by what agency the ejection 

 is effected. 



The fourth column gives the value of v to be expected 

 from the suggestions of columns 2 and 3. 



Discussion of Results. 



I. Broadly speaking, there is a general agreement between 

 the observed and calculated values of the effective fre- 

 quencies (v) for these X-ray electrons. 



Taking copper for example : The three lines of smallest 

 frequency are to be ascribed to the action of K a and Kp of 

 copper on the rings outside the K ring, and it is to be noted 

 that the central line of the triplet is to be regarded as due 

 to two sets of electrons — one from the L ring, the other 

 from the outer rings or even from free electrons. Further, 

 the line 217 ascribed to the ejection from the outer rings 

 (or possibly the lifting out of free electrons) * is very faint — 

 an observation in agreement with Rutherford and Ellis's 

 /9-ray results. 



This characteristic K triplet is repeated in the case of 

 zinc, arsenic, strontium, and molybdenum. In the case 

 of tungsten and bismuth, however, the K radiation is 

 not excited, and in place of the K triplet we get the 

 L quadruplet, the additional line being due to the presence 

 of three strong lines L a , L^, and L y in the L X-ray 

 spectrum. 



At the other end of the copper electron spectrum 

 are two lines, 502 and 552, very faint and probably due 

 to RhK a and RhK^, ejecting electrons from the outer rings 

 or lifting free electrons from the surface of the material 

 as a whole. The apparatus, of course, is not capable of 

 differentiating between these two possibilities. 



Of the four remaining lines, 270 is clearly due to a 

 K-ring electron ejected by the RhK a radiation, while 461 is 

 an L-ring electron ejected by the RhK^ radiation. 



The remaining two lines are rather puzzling. 287 is 

 a faint line, and may therefore be inaccurately measured, 

 but 313 is a strong well-defined line. The nearest straight- 

 forward interpretation is to place it as a K-ring electron 

 ejected by RhK^, in which case the expectation for v would 

 be 334. This is a far bigger difference than is to be expected 



* See Millikan, Phys. Rev. 1921, p. 243. 



