Atom switch

If this is subjected to the "Bain strain" it becomes an undistorted b.c.c. cell. This atomic "switching" involves the least shuffling of atoms. As it stands the new lattice is not coherent with the old one. But we can get coherency by rotating the b.c.c. lattice planes as well (Fig. 8.8). 

Once the atomic contributions FA are determined, the corresponding integrals IA are subsequently computed on grids that consist of points on concentric spheres around each atom. Switching to polar coordinates r, 0, and < ) the radial and angular integrations are separated according to... 

Eigler D, Lutz CP, Rudge WE (1991) An atomic switch realized with the scanning tunneling microscope. Nature 352 600... 

Joachim C, Sautet P, Lagier P (1992) The tip apex structure of the Eigler atomic switch. EuroPhys Lett 20 697... 

Yam, P. Atomic Turn-On First Atom Switch, Sci. Amer., 20 (November 1991). 

An STM manipulation mechanism related to the adsorption and desorption processes of single atoms and molecules is known as vertical manipulation (Fig. 10). This process involves transfer of single atoms or molecules between the tip and substrate and vice versa (Fig. 10(a)). An atomic switch realized by the repeated transfer of a Xe atom between the STM tip and a Ni(110) substrate is the first example of vertical manipulation [22]. The atom/molecule transfer process can be realized by using an electric field between the tip and sample, or by multiple excitations with inelastic tunneling electrons, or by making mechanical contact between the tip and atom/molecule. This transfer mechanism can be modeled by using a double potential well as shown in Fig. 10(b). At an imaging distance, approximately 6 A between tip and surface, the atom/molecule has two possible... 

The picture that emerges is that there is a considerable amount of atom switching events occurring before the onset of dissociation. It has been proposed that the reactive channels for exchange are vibrational states far below the bound limit e.g., i = 4 for deuterium [51]. The non-linear production of exchange products and the inert gas order dependence in the rate law identifies the exchange mechanism as a sequence of steps rather than one four-centre encounter. Whether or not atom switching is an important precursor to dissociation remains to be demonstrated. 

Terabe K, Hasegawa T, Nakayama T, Aono M (2005) Quantized conductance atomic switch. Nature 433 47-50... 

Solvents in which an oxygen donor atom has been replaced by a sulfur atom switch from hard to soft solvents. Tetrahydrofuran can thus be compared with tetra-hydrothiophene n = 0.00 and 0.80, respectively. Some other such solvent pairs are 7V,7V-dimethyl-thioformamide ( =1.35) compared to DMF (jU=0.11), N-methyl-thiopyrrolidinone (/<=1.35) compared to NMPy (/t = 0.13), diethylsulfide (fx=0.68) compared to diethylether ( /=0.00), and hexamethyl thiophosporamide (fi = 1.57) compared to HMPT fi=0.29). Solvents with nitrogen and phosphorus donor atoms are also soft, for example, pyrrole (/i=0.81) and aniline ( =0.75) [3]. 

Despite its simplicity, the model was applied with great success to, e.g., the STM-driven transfer of a xenon atom on a nickel surface. This pioneering experiment was the very first example of an STM-controlled atomic switch, where the xenon atom was moved from the nickel surface to the tungsten STM tip. Figure 6 shows the comparison between theoretical and experimental transfer rates for different values of the ratio The computed transfer rates are inferred from an implicit dynamics between truncated harmonic oscillators, with the initial conditions chosen as the fifth excited vibrational state located on the surface. This corresponds to a situation where above-threshold dynamics dominates. By construction, the rates exhibit the proper power-law dependence with increasing potential bias. It is found that, for this... 

Tsuruoka, T., Terabe, K., Hasegawa, T. et al. 2012 Effects of moisture on the switching characteristics of oxide-based, gapless-type atomic switches. Adv. Funct. Mater. 22 70-77. 

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