Paramagnetic direct correlation function

The behaviour of the paramagnetic spin susceptibility, x, is determined by the direct correlation function, [Eq. (100)]. This function can be fit in terms of real-space parameters ... 

The electron spin resonance (E.S.R.) spectra of a paramagnetic organic molecule, e.g. free radical, radical cation or radical anion, is directly related to its unpaired electron distribution (spin density). In the region of a magnetic nucleus the hyperfine interaction between the magnetic moments of the nucleus and the electron is a function of the spin density. It has been shown that, for an atom N, a direct correlation exists between its observed hyperfine coupling constant, and [pa—pP), the unpaired electron population of its atomic orbitals 1). 

Fig. 3 Distance measurements between paramagnetic centers by EPR spectroscopy. Below 0.5 nm. distance estimates are unreliable for 0.5

The effect of 1-D spin dynamics on the ESR line was investigated in various 1-D paramagnetic systems in the 1970s [20-23]. Basically, if the cutoff frequency is less than the linewidth, (Oc < A co, the divergence of f(cu) is felt on the line, which no longer has the Lorentzian shape derived from motional narrowing. The lineshape F(o>) can be analyzed either directly in the frequency domain or in the time domain by considering the total spin time correlation function, G(/) = (S (t)S (O)), with S = Sx-Sx, which is the Fourier transform of F((o) ... 

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