Heterospin system

The formula just derived for the magnetic susceptibility of heterospin systems is applicable also to the special case of homospin systems when the g-factors differ from each other. Notice that... 

Fig. 10.8. Temperature variation of the magnetic susceptibility (a) and the effective magnetic moment (b) for a heterospin system SA = 1/2 and = 1 gA = 2.0, gB = 2.0, solid— antiferromagnetic coupling (J/k = —100 K) dashed—ferromagnetic coupling (J/k — +100 K).

When we planned to use heterospin systems consisting of metal 3d spins and... 

Our carbene work aiming at the construction of molecular based magnets can be classified into two approaches, pure organic spin system [23] and heterospin system. In this section, we will present specific main works in both approaches in historical order. 

In this section on the heterospin system, we will discuss three subjects 1) the magnetic coupling between the metal ion and organic spins through pyridine chromophores, 2) the photochemical formation of ferri- and ferrimagnetic chain (ID), and 3) the attempt to create frozen solution magnets (a carbene-based magnet). 

Strategy in heterospin system for Molecular Based Magnet... 

The experiment described above is termed selective population transfer (SPT), or more precisely in this case with proton spin inversion, selective population inversion, (SPI). It is important to note, however, that the complete inversion of spin populations is not a requirement for the SPT effect to manifest itself. Any unequal perturbation of the lines within a multiplet will suffice, so, for example, saturation of one proton line would also have altered the intensities of the carbon resonance. In heteronuclear polarisation (population) transfer experiments, it is the heterospin-coupled satellites of the parent proton resonance that must be subject to the perturbation to induce SPT. The effect is not restricted to heteronuclear systems and can appear in proton spectra when homonuclear-coupled multiplets are subject to unsymmetrical saturation. Fig. 4.20 illustrates the effect of selectively but unevenly saturating a double doublet and shows the resulting intensity distortions in the multiplet structure of its coupled partner, which are most apparent in a difference spectrum. Despite these distortions, the integrated intensity of the proton multiplet is unaffected by the presence of the SPT because of the equal positive and negative contributions (see Fig. 4.19d). Distortions of this sort have particular relevance to the NOE difference experiment described in Chapter 8. 

There are 21 combinations of heterospin dinuclear systems between SA = 1/2 and SB = 7/2 local spins. The zero-field energy levels of the coupled systems can be generated in the same way as in the previous case of homospin systems. The result is... 

Isotropic exchange in heterospin dinuclear complexes differs from the homospin case in that the second-order van Vleck coefficients are also non-zero. The final formula for the magnetic susceptibility resembles the case of the narrow multiplets for mononuclear systems spin-orbit coupling can be formally substituted by spin-spin (exchange) coupling. However, the local atomic g-tensors should be properly combined into the molecular-state g-tensor. 

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