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THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1953 



substance of which the name and the structural diagram are included in 

 the figure. This is one of the strongest and sharpest electron-resonance 

 peaks on record. The gr- value is 2.0064 d= 0.0002; it is therefore almost 

 an ideal case, but the difference from the ideal value is sure and signifi- 

 cant. It would however be misleading to suggest that such a case is 

 t3^ical. 



What are called the ''strongly paramagnetic salts" form a group with 

 several features in common. They tend to have long names, and they 

 have complex chemical formulae; crystal lattices or at any rate unit-cells 

 which are non-cubic; and atoms some of which belong either to the 

 rare-earth elements or to the elements of the "first transition group," 

 iron or cobalt for instance. These atoms are likely to have two or more 

 uncompensated electrons in parallel coupling. I now recall what was 

 said about such coupled electrons in the introductory passage. 



8520 8540 8560 8580 8600 8620 8640 8660 8680 

 STATIC MAGNETIC FIELD IN OERSTEDS 



Fig. 2. — Electron resonance of porphyrexide. This is one of the strongest and 

 sharpest peaks of electron -resonance yet observed. The g-value is 2,0064 ± 0.0002, 

 which makes it slightly but significantly different from the ideal case. In the 

 structural diagram, the asterisk signifies a three-electron bond. (A. N. Holden, 

 W. A. Yaeger and F. R. Merritt). 



