Superparamagnetic clusters

The iron vapor-toluene reaction has evoked interest because of the lability of the proposed bis(arene)iron complex to ligand subsitu-tion and to loss of both toluene molecules to free the metal atom. In the latter case the toluene molecules may be usefully regarded as metal atom carriers which can be used to direct the latent reactivity of the atom in subsequent solution phase chemistry. In this way the metal atom experiment can benefit from the convenience and additional versatility afforded by bench-top chemical manipulations. These results are relevant to a reported preparation of a dehydroxy-lated silica-supported Fischer-Tropsch catalyst from a static reactor codeposition of Fe and toluene.(46) In the liquid phase, iron atoms "bottled" in this way have also been utilized in an exceedingly mild method for making minute catalytically active superparamagnetic clusters on the surface and within the cavities of a dehydrated sodium zeolite Y.(38) Using the rotary reactor, preformed solutions of solvated iron atoms (as the toluene complex) are cannulated below their decomposition temperature out of the flask to a cold slurry of the support in toluene. Diffusion of intact... 

Quian (Juiroga R, Nadasdy Z, Ben-Shaul Y (2004) Unsupervised spike detection and sorting with wavelets and superparamagnetic clustering. Neural Comput. 16(8) 1661-1687, Aug. 2004. 

The expression on the right-hand side of Equations 8.8 and 8.9 is the well-known Langevin function, and gives the characteristic dependence of the measured Pexpt on N, B, and T for a superparamagnetic cluster. When the thermal energy is larger than the Zeeman energy scale, N[iB k T, Equation 8.9 further reduces to... 

Figure 5.27 FC and ZFC magnetization versus the temperature plots taken at 100 Oe for the Zn /10jjO (x—0.01) sample. Note that the extrapolated slopes versus temperature are of opposite signs in the ZFC and FC curves and there is a significant deviation in these two values. This indicates a superparamagnetic cluster-type behavior. (Courtesy of M.H. Kane [122].)...

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