Tunneling decay constant

At loadings lower than 1 MX per 20 DNA bp, the fraction of the electrons captured by the intercalator was found to follow the relation D(t) = l/pln/c0t this assumes random MX intercalation in the DNA and an increase electron transfer to intercalator with ln(f) as expected for a single-step tunnelling process. The electron-transfer distances, after 1 min at 77 K, were about 8-10 bps for the most electron affinic intercalators MX and NPa. For these intercalators tunnelling decay constants p of 0.8 - 0.9 A, were reported with a /c0 = 1 x 10 s 1 in the standard relation for fall off of p with tunnelling distance, k = k0e bD. These... 

The transfer distance with time, D, and the value of the tunneling decay constant, /3 were determined in the rate constant expression for tunneling, k = kge °t. Table 1 shows the results for these studies for both hole and electron transfer with MX as both the electron and the hole acceptor. 

On the other hand, the low-conductance values (L) give a poor linear correlation of the molecular length with an approximate decay constant fiN 0.45 0.09, distinctively different from the H and M sequences. The estimated value of fiN(L) is rather close to results reported by Cui [28] and Haiss [243]. Haiss et al. [244] found a pronounced temperature dependence of these L values, which scales logarithmically with 7 1 in the temperature range 293-353 K, indicating a transport mechanism different from a simple tunneling model. 

The effective tunneling barrier may be quantified by measuring the distance dependence of the tunnel conductance or tunneling current [Eq. (1) or (2), respectively]. Experimentally, the decay constant, k, may be derived from dc or ac measurements. The more accurate ac modulation... 

In the following calculation, the value k 0.96A is taken. In the [Oil] direction and the [211] direction, the decay constants y of the corrugation component of the tunneling current are different. We denote them as... 

Thus, the study [45] of the kinetics of the charge recombination in the reaction centres of photosystem 1 of subchloroplasts over wide time and temperature intervals has shown an essential difference in the kinetics of the tunneling decay of P700+ at high and low temperatures. The quantitative description of the electron transfer kinetics has proved possible in terms of the assumption of a difference in charge recombination rate constants for different reaction centres. Such a difference may be due, for example, to a non-coincidence, for different reaction centres, of electron tunneling distances or to different conformational states of these centres. 

The theoretical description of a emission relies on calculating the rate in terms of two factors. The overall rate of emission consists of the product of the rate at which an a particle appears at the inside wall of the nucleus times the (independent) probability that the a particle tunnels through the barrier. Thus, the rate of emission, or the partial decay constant ka, is written as the product of a frequency factor,/, and a transmission coefficient, T, through the barrier ... 

If monomolecular decay of the donor particles with the rate constant k is possible along with tunneling decay by the reaction with the acceptor particles, the following expression describes the change of the concentration of the donor particles with time... 

Santos-Lemus and Hirsch (1986) measured hole mobilities of NIPC doped PC. Over a range of concentrations, fields, and temperatures, the transport was nondispersive. The field and temperature dependencies followed logn / El/2 and -(T0IT)2 relationships. For concentrations of less than 40%, a power-law concentration dependence was reported. The concentration dependence was described by a wavefunction decay constant of 1.6 A. To explain a mobility that shows features expected for trap-free transport with a field dependence predicted from the Poole-Frenkel effect, the authors proposed a model based on field-enhanced polaron tunneling. The model is based on an earlier argument of Mott (1971). 

The Ru-protein data points are scattered around the Ru azurin fi = 1.1 A exponential distance decay. More than three-fourths of the Ru protein ET rates fall in a 1.0 to 1.3 A y3-value zone. The data in Figure 5 suggest that a canonical distance decay constant will not describe long-range electron tunneling in proteins. Rates at a single distance can differ by as much as a factor of 10 and D/A distances that differ by as much as 5 A can produce identical rates. The... 

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