Coulombic binding

Because of its lower electron affinity, Te sites trap holes which can then coulombically bind an electron in or near the conduction band to form an exciton. Subsequent radiative collapse of this exciton leads to emission (10,11,12,13). In the context of the PEC, emission thus serves as a probe of electron-hole (e -h" ) pair recombination which competes with e - h+ pair separation leading to photocurrent. Except for intensity, the emitted spectral distribution is found to be independent of the presence and/or composition of polychalcogenide electrolyte, excitation wavelength (Ar ion laser lines, 457.9-514.5 nm) and intensity (<30 mW/cnZ), and applied potential (-0.3V vs. SCE to open circuit) (6,1,8,9). 

The fact that poly(acrylic acid) inhibits the reaction and that the neutral substrate PNPA(5), is not bound to the polymer, show the significance of the coulombic binding in the reaction. 

In the oxidation reaction of the anionic reactant, [Fe(II)-EDTA] with poly(4-vinylpyridine)-Co(III)en2 complex(XIII), the coulombic binding between the reactant and the polymer is considered (122-124). 

Table 6. Calculated differential Coulomb binding energy shifts due to change of valence s and d count in Tia)...

CP states or geminate pairs) Eqp = energy, Ucp = Coulomb binding energy, Q = dissociation probability of the CP states, r is the spacing of the molecule-ions A/T and M in the CP state, is the Coulomb radius kT = e jAnssQrc. c Ionised states Mp and Mp... 

The probability of this dissociation can be described in a modified Onsager model [29], [26-28]. Here, the activation energy for the intrinsic photo-generation of the free charge carriers is determined only by the Coulomb binding energy Ucp of the CP state ... 

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