Orbital energy transfer

Enolate anions (4e) that have been heated by infiared multiple photon absorption for which torsional motion about the H2C-C bond, which destabilizes the 7t orbital containing the extra electron, is the mode contributing most to vibration-to-electronic energy transfer and thus to ejection. 

The behaviour, which is not controlled by the topochemical rule but is greatly influenced by non-topochemical factors, is discussed in Section 2 in terms of molecular mobility, stabilization energy by orbital interaction and energy transfer in the crystals. 

Fig. 11. Top molecular orbital energies for precursor, structure C (broken lines) and for bridged intermediate, structure D (full lines). Bottom bridging energy (AE) for N =0 (full line) and N = 1 (broken line), where N is the number of electrons transferred from the carbon residue to the platinum. The energies are plotted as functions of the 7rC3-to-platinum overlap integral (S). The energy unit 0 [ is the absolute value of the exchange integral between a pair of p1 orbitals in benzene. For structures C and D, cf. reaction (7). After J. R. Anderson and N. R. Avery, J. Calal. 7, 315 (1967).

FRET efficiency can be quantitatively measured over D-A separations of 0.5-10 nm. For shorter distances the assumption of point dipoles may not be valid (although this does not seem to be noticeable until very short distances). Very short distances comparable to the spatial extension of electron orbitals can lead to energy transfer by electron transfer (Section 1.11). 

In contrast to the dipole-dipole interaction, the electron-exchange interaction is short ranged its rate decreases exponentially with the donor-acceptor distance (Dexter, 1953). This is expected since, for the electron exchange between D and A, respective orbital overlap would be needed. If the energy transfer is envisaged via an intermediate collision complex or an exciplex, D + A—(D-------A)- D + A, then Wigner s rule applies there must be a spin com-... 

In Eq. (3.4), the contributions of both the nuclei and the electrons are considered. The maximum energy transfer for electrons is (l/4)mv2, but since their contribution to the loss cross section is small, no great error is committed in taking the maximum energy transfer as 2mv2 for all ionizations represented in Eq. (3.4). Electron capture is a three-body process best visualized as ionization of a molecule of the medium with the ejected electron having a speed v at least equal to that of the incident ion, followed by capture of that electron in an orbit around the impinging ion. Mozumder et al. (1968) modified an earlier formula of Bohr (1948) and wrote the capture cross section as... 

---