Acceptor states

Chattoraj M, Chung DD, Paulson B et al (1994) Mediated electronic energy transfer effect of a second acceptor state. J Phys Chem 98 3361-3368... 

In the fluctuation band of electron energy of hydrated redox particles, the donor band of the reductant is an occupied band, and the acceptor band of the oxidant is a vacant band. The level erotsDcno at which the donor state density equals the acceptor state density (Aai/e) = Dox(e)) is called the Fermi level of the redox electron by analogy with the Fermi level e, of metal electrons [Gerischer, 1961]. From Eqns. 2—48 and 2—49 with f BED(e) =-DoxCe), we obtain the Fermi level Tiixxox.) (the redox electron level) as shown in Eqn. 2-51 ... 

In this expression, denotes the acceptor states (monomer, dimer, etc.), revalues describe the numbers of binding sites per molecule of the acceptor in each of its ohgomeric states, the K s are hgand binding equihbrium constants, and S is the hgand. 

For implanted acceptor activation there have been several reviews during the last few years since Troffer et al. s often-cited paper on boron and aluminum from 1997 [88]. Aluminum is now the most-favored choice of acceptor ion despite the larger mass, which results in substantially more damage compared with implanted boron. Mainly it is the high ionization energy for boron that results in this choice, as well as its low solubility. In addition, boron has other drawbacks, such as an ability to form deep centers like the D-center [117] rather than shallow acceptor states and, as shown in Section 4.3.2, boron ions also diffuse easily at the annealing temperatures needed for activation. The diffusion properties may be used in a beneficial way, although it is normally more convenient if the implanted ion distribution is determined by the implant conditions alone. 

The introduction of Fca-atom vacancies modifies the energy diagram of Fig. 3. The preservation of local charge neutrality requires that each Fea-atom vacancy have five of its six nearest neighbors as Fee ions, which means that the ai(, ) states of five Fea ions neighboring a vacancy, , are raised an energy Ea above the Fermi energy. They become acceptor states inaccessible to the mobile electrons at low temperatures. It is possible to express this situation with the structural formula... 

Hamiltonian term describing the interaction between the bridge state B ) and the acceptor state A)... 

Rate constant for charge transfer between donor and acceptor Effective coupling between donor and acceptor states Matrix element of Hamiltonian between diabatic donor and acceptor states... 

Overlap integrals between donor and acceptor states Energy gap between adiabatic states... 

Thus, the electronic coupling is equal to the Hamiltonian matrix element Hda between donor and acceptor states. Recently, this relation was employed to estimate the coupling between nucleobases in DNA fragments [32]. Our estimates showed that both terms in Eq. 5, Hda and Sda Hdd+Haa)> are of the same order of magnitude for the coupling between nucleobases. Thus, Eq. 6 is a rather crude and unnecessary approximation of Eq. 5. 

The GMH method of Cave and Newton [39, 40] is based on the assumption that the transition dipole moment between the diabatic donor and acceptor states vanishes, i.e., the off-diagonal element of the corresponding dipole moment matrix is zero. Thus, in the localization transformation one diagonalizes the dipole moment matrix of the adiabatic states ij/i and ij/z. For a two-state model, the rotation angle ft) can be expressed with the help of the transition dipole moment and the difference of the dipole mo-... 

If donor and acceptor are in resonance, Aqi=Aq2=0 in Eq. 15 or Aq=0 in Eq. 16, then both FCD expressions reduce to Eq. 7. Also, when considering a CT system, it is often informative to estimate the energy gap Eg-Ed between the diabatic donor and acceptor states. From Eq. 9, one directly obtains... 

If donor and acceptor states are degenerate, = then cos2ft)=0 and, therefore, sin2< =l then, in line with Eq. 10, the electronic coupling is determined by half of the adiabatic energy splitting, Eq. 7. 

Equation (B29) is a generalization of the simple charge-balance equation represented by Eq. ( 17). Inclusion of centers that can have both donor and acceptor states results in a slight modification of Eq. (B29), and will be considered in the next section. 

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