Two-terminal configuration

In order to obtain estimates of quantum transport at the molecular scale [105], electronic structure calculations must be plugged into a formalism which would eventually lead to observables such as the linear conductance (equilibrium transport) or the current-voltage characteristics (nonequilibrium transport). The directly measurable transport quantities in mesoscopic (and a fortiori molecular) systems, such as the linear conductance, are characterized by a predominance of quantum effects—e.g., phase coherence and confinement in the measured sample. This was first realized by Landauer [81] for a so-called two-terminal configuration, where the sample is sandwiched between two metalhc electrodes energetically biased to have a measurable current. Landauer s great intuition was to relate the conductance to an elastic scattering problem and thus to quantum transmission probabilities. 

Fig. Ic. Postulated movements of the various/, t2g and band features under pressure, for the two terminal configurations / and d in SmS. The latter condition holds for P > 50 kB.

Another configuration having power collection from only two terminals is the Hall generator shown in Figure 5d. In this configuration, opposing electrode pairs are connected, and the current flow for power extraction is axial. E = 0, and... 

Figure 12.8. Transient effect of an applied potential, UAP, between the two terminal gold electrodes (30 V) on the catalytic rate of ethylene oxidation (expressed in mol O/s) for dotted (filled circles) and multi-striped (open circles) platinum configuration.10 Reprinted with permission from Elsevier Science.

The synthesis of [3]- (figuratively shown as 7) and a [5]rotaxane (8) with one central and two terminal porphyrins in the open configuration has been reported <96AG(E)906> also a rotaxane with two Ru(terpy>2 stoppers has appeared <96CC1915>. A pseudorotaxane comprised of a macroring of 2,9-diphenyl-1,10-phenanthroline unit and a molecular string... 

The configuration of the C, 2 chain has been determined spectroscopically (72). Bearing in mind that the two terminal 77-allyl groups in the Cl2 chain may be mutually cis or trans (71a, 71b) to each other, and also that the molecule contains a trans double bond, the six isomers (XXXVI)-(XLI) are possible. Rotation of one of the 77-allyl groups relative to the other gives a further six possibilities this is illustrated for (XLII). This type of isomerization has been discussed elsewhere in relation to the structure of bis(77-crotyl)nickel (13). 

---