Critical nearest-neighbor distance

Table 7.9 The critical distance Ro and the mean nearest-neighbor distance Ri, + i (both calculated for pentacene guest occupying O4 sites) along the three axes of the pseudo-monoclinic unit cell of...

For the above mentioned FePt particles, the particle diameter is clearly smaller than the critical particle size given by Eq. (8) for coherent rotation. Furthermore the strength of the magnetostatic interaction field acting on nearest neighbor particles is only about 2% of the anisotropy field for a particle distance of 2 nm. Thus the Stoner-Wohlfarth theory can be applied. 

X./. 247i2o nm. These values are compared in Table I with values obtained for K3C6o- for the Rb compound is somewhat smaller than obtained in the case of K3C60 but still larger than the nearest-neighbor C60 distance d (ca. I nm). We also estimate the thermodynamic critical field from //. (O)-7/H(0)//,2(0)/lnic (Ref. [14]) and compare it to K3C60 in Table I. 

In spite of impressive experimental demonstrations of basic quantum information effects in a number of different mesoscopic solid state systems, such as quantum dots in semiconductor microcavities, cold ions in traps, nuclear spin systems, Josephson junctions, etc., their concrete implementation is still at the proof-of-principle stage [1]. The development of materials that may host quantum coherent states with long coherence lifetimes is a critical research problem for the nearest future. There is a need for the fabrication of quantum bits (qubits) with coherence lifetimes at least three-four orders of magnitude longer than it takes to perform a bit flip. This would involve entangling operations, followed by the nearest neighbor interaction over short distances and quantum information transfer over longer distances. 

In spite of diverging predictions of surface proton diffusion coefficients, the studies quoted above provide consistent accounts of the impact of monolayer composition, reduced dimensionality, and interfacial ordering on proton dynamics. Altogether, there is ample evidence for efficient surface proton transport, which is sensitive to the packing density and chemical nature of acid headgroups. Surface pressure, surface electrostatic potential, and lateral proton conductivity increase dramatically upon monolayer compression below a critical area with typical values in the range of 25 to 40 K per SG. This critical area corresponds to a nearest-neighbor separation distance of SG of 6.5-7 A (Leite et al., 1998 Mitchell, 1961). 

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