368 



DR. W. M. HICKS : A CRITICAL STUDY OF SPECTRAL SERIES. 



separation 308 '99 corresponds to the displaced <$, sequent for m = 2. It thus supports 

 the explanation adopted for the triplet modification. 



For reference the multiples of the oun giving the satellite separations are collected 

 in the following table, where d lt d 2 refer to the first and second line in a satellite set. 



JiTrF. The F lines form parallel series in which the constant separations depend on 

 the satellite separations of the D series. In other words the limits are the d(l) 

 sequents which form the satellites. Now it has been shown above that the abnormal 

 triplet separations which the D series exhibit is probably due to the fact that the d 

 sequent for a given satellite triplet is not the same for each of the three lines, but 

 that they are subject to a displacement of one or more ouns. For instance where v 1 is 

 788 in place of 786 (in round numbers) the difference 2 is due to the fact that d 2n is 

 not equal to d ln but is d ln (Si). If the strongest line is to be taken as normal, we 

 should expect the d 3n , or d 2n to be normal rather than d ln as D ln is always weaker 

 than the other lines of a triplet satellite. In this case F re (co) = d ln (Si) and the 

 F separation = F n ( ) Fj ( oo) = d ln (Si)d n which is less than the observed satellite 

 separation by about 2. As a fact we do find these diminished separations. In 

 searching for F lines therefore we have to examine the spectrum for wave-lengths 

 longer than d u and showing as multiplets with separations the same as the satellite 

 separations or less. In the particular case of Kr these are 100, 105, 133, 213, 307, 

 1048, I860,* and we are to expect series which we will denote by F M with n from 1 to 8. 

 From this point of view it is unfortunate that allowance has to be made for the rule 

 as to the excessive displacements occurring in the lower orders (m = 2, 3) and that 

 a complete multiplet, showing all the above separations, is not to be expected. With 

 D u (l) = 20976-63 and D! ( oo) = 51655'56 + d n = 30678'93 + = F, (oo). The 

 mantissa of/ is in general large, say, beween 7 and '99. Consequently the region 

 in which F 2 (2) is to be found is where the wave-number is less than 30768 -N/(2'99) 2 , 



t There may, of course, be others depending on D lines other than those considered in the text. 



