Tunnel magnetic

A wide variety of measurements can now be made on single molecules, including electrical (e.g. scanning tunnelling microscopy), magnetic (e.g. spin resonance), force (e.g. atomic force microscopy), optical (e.g. near-field and far-field fluorescence microscopies) and hybrid teclmiques. This contribution addresses only Arose teclmiques tliat are at least partially optical. Single-particle electrical and force measurements are discussed in tire sections on scanning probe microscopies (B1.19) and surface forces apparatus (B1.20). 

Key Words—Carbon nanotubes, scanning tunneling microscopy, spectroscopy, magnetoresistance, electrical resistivity, magnetic susceptibility. 

Spin-polarised scanning tunnelling microscopy (SP-STM) Magnetic force scanning tunnelling microscopy (MF-STM)... 

In the theory of deuteron spin-lattice relaxation we apply a simple model to describe the relaxation of the magnetizations T and (A+E), for symmetry species of four coupled deuterons in CD4 free rotators. Expressions are derived for their direct relaxation rate via the intra and external quadrupole couplings. The jump motion between the equilibrium positions averages the relaxation rate within the same symmetry species. Spin conversion transitions couple the relaxation of T and (A+E). This mixing is included in the calculations by reapplying the simple model under somewhat different conditions. The results compare favorably with the experimental data for the zeolites HY, NaA and NaMordenite [6] and NaY presented here. Incoherent tunnelling is believed to dominate the relaxation process at lowest temperatures as soon as CD4 molecules become localized. 

While this generally has only small effects on the static magnetic properties, it may play a relevant role in providing a quantitative agreement with experimental resonance data, and in explaining quantum tunnelling relaxation of the magnetization at low temperature [51]. 

Gatteschi, D. and Sessoli, R. (2003) Quantum tunneling of magnetization and related phenomena in molecular materials. Angew. Chem. Int. Ed., 42,... 

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