569 



TABLE 612.— VALUES OF THE WAVELENGTH OF THE CADMIUM RED LINE 

 IN TERMS OF THE INTERNATIONAL METER (Unit = 1 X 10 ~ 10 m ) 



The values originally reported (column 3) are corrected (column 4) to take account of 

 subsequent conclusions (a) regarding the values to be attributed to the standards of length 

 employed, and adjusted (b), so far as the available information permits, to uniform stand- 

 ard conditions of dry air at 15°C and 760 mmHg pressure, containing 0.03 percent C0 2 . 

 The statistical mean deviation associated with the average value of 6438.4696 X 10~ 10 m 

 derived from these nine determinations amounts to ± 0.0010 X 10" 10 m. 



The recent production of purer monochromatic radiation (than the cadmium red line) 

 suggests that eventually another wavelength from a single heavy isotype of even mass 

 number may be adopted as the primary standard of length. Thus, since 1945 many milli- 

 grams of Hg 108 have been made by transmutation of gold in chain-reacting uranium piles. 

 Electrodeless lamps containing Hg 198 have been made and distributed by the National 

 Bureau of Standards. When excited by ultra-high frequency ( > 100 megacycles) and 

 water cooled these lamps emit with high intensity ideally sharp mercury lines. Preliminary 

 measurements, relative to Cd 6438.4696 A, of the' yellow and green lines of Hg 198 have 

 been reported 182 by the National Bureau of Standards, by the National Physical Labora- 

 tory, and by the International Bureau of Weights and Measures, as in Table 610. 



182 For reference, see p. 578. 



TABLE 613.— RESULTANT S VALUES AND TERM MULTIPLICITIES 



Number of 

 electrons 



1 



2 

 3 

 4 

 5 

 6 

 7 

 etc. 



5 



1/2 



0, 1 



1/2, 3/2 



0, 1, 2 



1/2, 3/2, 5/2 



0, 1, 2, 3 



1/2, 3/2, 5/2, 7/2 



Term multiplicities 



Doublets 

 Singlets, triplets 

 Doublets, quartets 

 Singlets, triplets, quintets 

 Doublets, quartets, sextets 

 Singlets, triplets, quintets, septets 

 Doublets, quartets, sextets, octets 



SMITHSONIAN PHYSICAL TABLES 



