General Characteristics of the Magnetic Field

GENERAL CHARACTERISTICS OF THE MAGNETIC FIELD 5.1.1 A permanent (direct) electric current... 

Thus we may state that the matrix elements of the Lyman series transitions increase with the increase of the magnetic field. Similar increase is also characteristic of matrix elements for 7r-transitions to the state 2pl and n- and cr-transitions to the state 2s of the Balmer series. However this property does not hold in general. E.g. for 7r-transitions to the state 2p0 from many states of the upper-level diamagnetic manifold the coefficient q 0A 2po takes negative values (see table 2). So the magnetic field action on the radiative matrix elements is rather selective and depends on the structure of initial and final states and on the type of transition (7T or cr). 

In general, when we have a system of confocal shells calculation of the secondary field caused by the m-harmonic of the primary field can be performed in the following way. First of all, three characteristics — Wem, Wim and — of two shells, located closer to the source of the primary field than others are calculated. Then they are replaced by one shell, which is equivalent to them, and its characteristics are defined from eqs. 3.39, 3.40 and 3.44. After this the screening and reflection coefficients of the third shell are calculated and then the characteristics of the shell which is equivalent to all three shells are defined. This process continues until all shells are replaced by one which is equivalent to all of them. Calculations are made using eq. 3.39, 3.40 and 3.44, while characteristics of every shell are defined from eqs. 3.21, 3.22 and 3.30. As has been mentioned above these coefficients are expressed through well known functions with real arguments. The final expression for the field will be obtained after summation of the secondary fields, caused by all harmonics of the primary field. It is clear that components of the magnetic field are defined from Maxwell s equation ... 

As is generally known, electron spin resonance reveals the presence of unpaired electrons. This is of course characteristic of free radicals and the most well known stable free radical is a, a-diphenyl-0-picrylhydrazyl(DPPH) (1,213). In the ESR spectrum it gives a narrow signal close to free spin value g 2.0036 and is used for calibrating the magnetic field (2). 

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