g zz ¼ 2 À 8f=D
g xx;yy ¼ 2 À 2f=d
4.3.7 g Tensor Dependence on the Energy Level Trend
of the Paramagnetic Centers
In the case of valence electrons
g ij ¼ g e À 2f
X
n¼w 0
\w 0 L i
j jw n [ \w n L j
w 0 [
E 0
n À E
0
0
In the case of gap electrons
g ij ¼ g e À 2f
X
n6 ¼w 0
\w 0 L i
j jw n [ \w n L j
w 0 [
E 0
n À E
0
0
E 0 near C B g g e
Let us observe that the expression indicates the free electron g value, perturbed
by the contribution of the angular momentum, weighted on the energy differences
among the interacting states.
Fig. 4.10 shows some examples of ESR spectra in different physical states.
H 3 C
H 2 C
CH 3
CH 3
CH 2
x
C
C
C
C
C
Co
C N
N
O
O
-H 3 C
(E)
(D)
(C)
Liquid crystal
Co(meacacen)
H
H
g 1
g 2 g 3
Frozen solution
Frozen liquid crystals
oriented as C
Frozen liquid crystals
oriented at 90° from C
CoMe Acacen spectra in liquid crystal
(A)
(B)
Fig. 4.10 Some examples of electron spin resonance spectra in different physical states
4.3 Electron Spin Resonance
81