INTIMATE STRUCTURE ON COOLING. 



83 



In the above, the reversals which connect fluorescence to absorption 

 series have been sought for in the seventh group. There are, however, 

 other possible connections, for coincidences occur in the sixth and 

 eighth groups as well. Since, as has already been pointed out, the 

 difference in spacing between a fluorescence and absorption interval 

 is nearly the same as the spacing between fluorescence bands, it is often 



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POTASSIUM URANYL CHLORIDE 



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AMMONIUM URANYL CHLORIDE 



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I 



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RUBIDIUM URANYL CHLORIDE 



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_B_L 



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CAESIUM URANYL CHLORIDE 



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FIG. 69. 



possible to join equally well two fluorescence series to one absorption 

 series, a fact which makes it difficult to determine the true relation in 

 the case of this class of salts. 



The actual manner in which the reversals between fluorescence and 

 absorption occur is shown in figure 69, which is a diagram of the revers- 

 ing region. Here the plotting is quite accurate, the fluorescence bands 

 above and the absorption bands below the horizontal. Dotted lines 

 ndicate computed positions. This figure is approximately 10 times as 



