Coupled transitions

Mason SF (1980) The Ligand Polarization Model for the Spectra of Metal Complexes. The Dynamic Coupling Transition Probabilities. 39 43-81 Massey V, see Hemmerich P (1982) 48 93-124... 

The potential energy curves (Fig. 1), the non-adiabatic coupling, transition dipole moments and other system parameters are same as those used in our previous work (18,19,23,27). The excited states 1 B(0 ) and 2 B( rio) are non-adiabatically coupled and their potential energy curves cross at R = 6.08 a.u. The ground 0 X( Eo) state is optically coupled to both the and the 2 R( nJ) states with the transition dipole moment /ioi = 0.25/xo2-The results to be presented are for the cw field e(t) = A Yll=o cos (w - u pfi)t described earlier. However, for IBr, we have shown (18) that similar selectivity and yield may be obtained using Gaussian pulses too. 

In an earlier work, we have proposed a theoretical procedure for the spectroscopy of antiferromagnetically (AF) coupled transition-metal dimers and have successfully applied this approach to the electronic absorption spectrum of model 2-Fe ferredoxin. In this work we apply this same procedure to the [Fe2in - 82) P o - CeH48)2)2 complex in order to better understand the electronic structure of this compound. As in our previous work" we base our analysis on the Intermediate Neglect of the Differential Overlap model parameterized for spectroscopy (INDO/S), utilizing a procedure outlined in detail in Reference 4. 

Figure 6.4. Energy level diagram for a donor D and an acceptor A pair with an elec- D tronic energy difference AE. Possible coupled transitions are indicated.

Coulombic energy transfer is sometimes called resonance energy transfer because the energies of the coupled transitions are identical, or in other words, in resonance (Figure 6.10). 

Fig. 4.12. Energy level scheme of donor and acceptor molecules showing the coupled transitions in the case where vibrational relaxation is faster than energy transfer (very weak coupling) and illustration of the integral overlap between the emission spectrum of the donor and the absorption of the acceptor.

Dehydrogenative Coupling. Transition-metal catalyzed polymerization of silanes appears to hold promise as a viable route to polysilanes. A number of transition-metal complexes have been investigated, with titanium and zirconium complexes being the most promising (105—108). Only primary silanes are active toward polymerization, and molecular weights are rather low. The dehydrogenative polymerization is depicted in reaction 11, where Cp = cyclopentadienyl ... 

Simultaneous pair transitions Simultaneous electronic transitions in two coupled absorbers or emitters. Because of the coupling, transitions which are spin-forbidden in one of the centres might become spin allowed (spin flip). 

Mason, S. F. The Ligand Polarization Model for Ae Spectra of Metal Complexes The Dynamic Coupling Transition Probabihties. Vol. 39, pp. 43-81. 

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