Tunneling suppression

The final results, including the corrections noted above and the quantal tunneling suppression of the activation barrier -2 kcal/mol, of which more than 50 % comes from solvent modes), are summarized in Table 7. (We note that nuclear tunneling is expected to make only a minor, negative, contribution to [160]). 

To study the electrical transport properties of this double-barrier system Pd nanoclusters have been trapped in this gap. Figure 14 shows a typical l(U) curve. The most pronounced feature at 4.2 K is the Coulomb gap at a voltage of about 55 mV, which disappears at 295 K. Above the gap voltage, the l(U) curve is not linear, but increases exponentially, which was explained by a suppression of the effective tunnel barrier by the applied voltage. 

Bacterial attack is an early stage in the degradation of wood exposed in wet or moist conditions. Bacteria can be the dominant form of attack when fungal decay is suppressed by a wood-preserving treatment. Bacteria can attack the cell wall of wood by tunnelling, cavitation or erosion mechanisms (Eaton and Hale, 1993). 

Fig. 14.6. Effect of averaging to the normalized tunneling conductivity. Normalization of the conductivity spectrum by broadening. Even with a small AE, the noise is substantially suppressed. (Reproduced from MSrtensson and Feenstra, 1989, with permission.)...

M. Quack Tunneling will be completely suppressed if AEpv AEtun- Even if that is not the case, if A pv is negligible, tunneling may be exceedingly slow, as was already discussed by Hund in 1927 (see Refs. 1 and 2 and references cited therein). 

With decreasing further the sample length and temperature, resonant tunneling (RT) through a single localized state can be seen. It has been predicted that in this case the suppression factor F is equal to (r + Tj ) / (IT + Tr)2 [6], where are the leak rates from the state to the left and right contacts. 

---